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The number of undocumented immigrants in the United States: Estimates based on demographic modeling with data from 1990 to 2016

• Mohammad M. Fazel-Zarandi,
• Jonathan S. Feinstein,
• Edward H. Kaplan

ten

• Published: September 21, 2018
• https://doi.org/ten.1371/journal.pone.0201193

Figures

Abstract

We apply standard demographic principles of inflows and outflows to guess the number of undocumented immigrants in the Us, using the best available data, including some that have only recently go available. Our analysis covers the years 1990 to 2016. We develop an estimate of the number of undocumented immigrants based on parameter values that tend to underestimate undocumented immigrant inflows and overstate outflows; we also show the probability distribution for the number of undocumented immigrants based on simulating our model over parameter value ranges. Our conservative approximate is xvi.7 meg for 2016, nearly fifty percent college than the most prominent current estimate of 11.iii meg, which is based on survey data and thus different sources and methods. The mean estimate based on our simulation analysis is 22.one 1000000, substantially double the current widely accepted estimate. Our model predicts a like trajectory of growth in the number of undocumented immigrants over the years of our analysis, but at a higher level. While our analysis delivers different results, we note that it is based on many assumptions. The most disquisitional of these concern edge apprehension rates and voluntary emigration rates of undocumented immigrants in the U.Southward. These rates are uncertain, especially in the 1990's and early 2000'due south, which is when—both based on our modeling and the very different survey information approach—the number of undocumented immigrants increases nigh significantly. Our results, while based on a number of assumptions and uncertainties, could help frame debates well-nigh policies whose consequences depend on the number of undocumented immigrants in the U.s..

Citation: Fazel-Zarandi MM, Feinstein JS, Kaplan EH (2018) The number of undocumented immigrants in the The states: Estimates based on demographic modeling with data from 1990 to 2016. PLoS ONE xiii(ix): e0201193. https://doi.org/10.1371/journal.pone.0201193

Editor: Jeremy D. Goldhaber-Fiebert, Stanford University, Usa

Received: Oct 2, 2017; Accepted: July 10, 2018; Published: September 21, 2018

Copyright: © 2018 Fazel-Zarandi et al. This is an open access article distributed under the terms of the Creative Eatables Attribution License, which permits unrestricted utilize, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are inside the paper, its Supporting Information file, and accompanying Excel spreadsheet.

Funding: The authors received no specific funding for this work.

Competing interests: The authors have declared that no competing interests be.

Introduction

Immigration policy remains a hotly debated issue in the The states, with perhaps no attribute more controversial than how to address undocumented immigrants who exercise not take legal status. Policy debates about the amount of resources to devote to this upshot, and the merits of culling policies, including deportation, amnesty, and edge control, depend critically on estimates of the number of undocumented immigrants in the U.S., which sets the calibration of the issue. The most widely accustomed estimate of this number currently is approximately 11.3 1000000 [1, 2]. This estimate is based on variants of the residuum method [ii–4]. In this method, the size of the unauthorized immigrant population residing in the The states is set up equal to the estimate of the total foreign-born population minus the legally resident foreign-built-in population. The total foreign-born population gauge is derived from surveys that ask respondents whether they were born outside of the Usa (and whether they are American citizens), specifically either the American Community Survey or the Current Population Survey. The legally resident foreign-born population is estimated using administrative data on legal admissions.

An alternative approach to estimating the size of the undocumented population follows directly from basic demographic principles. Starting from a known population size at a given date, the population size at a futurity date equals the starting value plus the cumulative inflows minus the cumulative outflows. We employ this approach to estimate the number of undocumented immigrants in the U.S. for each twelvemonth from 1990 to 2016, using the best available data and parameter values from the academic literature and government sources. Some of the data we use has been collected and fabricated bachelor just recently, so our approach is timely.

Our analysis has 2 main outputs. Commencement, we generate what we phone call our conservative estimate, using parameter values that intentionally underestimate population inflows and overestimate population outflows, leading to estimates that will tend to underestimate the number of undocumented immigrants. Our conservative estimate for 2016 is sixteen.seven million, well higher up the estimate that is most widely accepted now, which is for 2015 but should be comparable. Our model also as almost work in the literature indicates that the population size has been relatively stable since 2008; thus 2015 and 2016 are quite comparable. For our 2nd step, recognizing that there is pregnant uncertainty nigh population flows, we simulate our model over a wide range of values for primal parameters. These parameter values range from very conservative estimates to standard values in the literature. We sample values for each key parameter from uniform distributions over the ranges we establish. In our simulations, we besides include Poisson population uncertainty conditional on parameter values, thus addressing the inherent variability in population flows. Our simulation results produce probability distributions over the number of undocumented immigrants for each twelvemonth from 1990 to 2016. The results demonstrate that our conservative estimate falls towards the lesser of the probability distribution, at approximately the 2.5th percentile. The mean of the 2016 distribution is 22.ane million, which we take equally the best overall gauge of the number of undocumented immigrants based on our modeling approach and current information. We likewise bear witness the variability in our model based on the simulations for each year from 1990 through 2016.

Methods

The model works as follows (mathematical formulation, parameter values, and data sources underlying this model are detailed in the Supporting Information). For our bourgeois estimate we begin with a starting 1990 population of 3.5 million undocumented immigrants, in agreement with the standard estimate [1]. The judge of 3.5 million undocumented immigrants in 1990 is based on applying the residuum method (using the 1980 and 1990 censuses), described previously, which we debate systematically underestimates the population. Thus in assuming an initial population of 3.5 1000000, and centering our simulations around this value, we are nigh certainly underestimating the size of the undocumented immigrant population at this engagement. In the simulations we assume that the starting population is drawn from a Poisson distribution with a mean of three.five one thousand thousand. It then follows that the population size at a futurity date equals the starting value plus the cumulative inflows minus the cumulative outflows.

Population inflows

Population inflows are decomposed into ii streams: (I) undocumented immigrants who initially entered the country legally simply have overstayed their visas; and (Ii) immigrants who have illegally crossed the border without being apprehended. We depict our approach for each source, explicate the ground for our assumptions and why they are bourgeois, and listing parameter ranges for the simulation.

(I) Visa overstays are estimated using Department of Homeland Security (DHS) data for 2016, the kickoff yr for which visa overstays were comprehensively measured [5]. To apply this data in our context nosotros as well gather data for not-immigrant visas issued for all years from 1990 [six]. For our bourgeois estimate nosotros assume that for each year the rate of overstays was equal to the 2016 rate. Calibration of our model shows that this supposition is in fact quite conservative. In particular, approximately 41% of undocumented immigrants based on the current survey information approach are visa overstayers [7], which translates to a visa overstay population of 4.6 1000000 in 2015. Our model however predicts the number of overstayers to be less than this (even though our overall estimate of the number of undocumented immigrants is higher). That is, in our model most undocumented immigrants are non overstayers, and the model produces an estimate of the number of overstayers beneath the gauge produced in the conventional approach based on survey data. We compute that we would demand to set the visa overstay rate to a higher place the DHS 2016 charge per unit, specifically 1.i times that rate, for our bourgeois approximate to generate as many overstayers equally the 4.6 1000000 in the xi.3 million estimate. Since many overstayers leave or adjust their status within a few months of their visa expiration date, we brand a further conservative adjustment and count as overstayers only those individuals who have overstayed more than 1 twelvemonth. For the simulation, we set up the visa overstay rate equal to the 2016 charge per unit multiplied by a compatible draw from the range [0.5,one.five]; consistent with the discussion in a higher place, this is a relatively conservative range.

(Ii) Illegal Border Crossers: We estimate illegal edge crossers through application of the standard repeated trials (capture-recapture) model [8–10]. The model requires as inputs statistics on the total number of border apprehensions, the number of individuals apprehended more than than in one case in a yr (recidivist apprehensions), and estimates of the deterrence charge per unit—the fraction of individuals who give up later being apprehended and do not try some other crossing. Given these inputs, the repeated trials model generates estimates of: (i) the anticipation rate—the probability an individual is caught trying to cross the border; and (ii) the total number of individuals who are non apprehended (they may be defenseless i or more than times simply cantankerous successfully on a later attempt) and enter the interior of the land illegally—the number of illegal border crossers in a twelvemonth. We discuss data sources and potential weaknesses of this approach here; more than information and mathematical details are provided in the Supporting Data.

DHS [10, 11] provide figures for the full number of edge apprehensions for every yr in our timespan. They too provide information on the number of recidivist apprehensions and estimates of the deterrence rate for every year from 2005. Based on these figures and estimates they provide an approximate of the anticipation rate for each year from 2005 to 2015. Their gauge is 35% for 2005 and increases steadily, to above fifty% past the end of the sample menstruum. From their estimates nosotros are able to derive directly estimates of the number of illegal border crossers for each of these years. For earlier years (1990 to 2004) we must make further assumptions. Our assumptions are about the apprehension and deterrence rates, since these take been addressed in the literature; in turn we are able to generate estimates of the number of illegal edge crossers in earlier years based on these assumptions (see the Supporting Data for analytic details).

Most experts concur that the anticipation charge per unit was significantly lower in before years [12, xiii]. A recent study [12] using information from the Mexican Migration Projection estimates this rate for every year from 1990 to 2010; estimates in the 1990'due south brainstorm from the low twenties and range up to approximately 30%. A second study estimates the charge per unit for 2003 at around twenty% [thirteen]. Given these estimates, and the general view that apprehension rates have risen, for our conservative estimate we assume that the anticipation charge per unit in years 1990-2004 was equal to the average rate in years 2005-10 or 39%; this is well above the rates discussed in the literature for earlier years and thus tends to reduce our estimate of the number of undocumented immigrants since it implies a larger fraction are apprehended at the border. For our simulation nosotros assume a uniform distribution over the range [0.25,0.40] for the earlier years, still above the boilerplate rates in the literature for these years.

Boosted facts support the view that the anticipation charge per unit has increased in recent years. The number of border agents has increased dramatically over the timespan of our assay [fourteen], and the number of hours spent past border agents patrolling the immediate border area has increased by more than 300% between 1992- 2004 [15]. Further, new infrastructure (e.g., fences) and technologies (e.k., nighttime vision equipment, sensors, and video imaging systems) were also introduced during this period [15]. Thus the apprehension rate we utilize for earlier years almost certainly overstates the actual apprehension rate and therefore underestimates the number of successful crossings. However, we note that these additional border resource may have been concentrated in certain locations and it remains a possibility that anticipation rates were higher in before years. Nosotros note finally that in using data only on Southern Edge crossings we again are conservative in our approach, non bookkeeping for illegal crossings along other borders.

Yet our view that we brand conservative choices in setting upwardly our model and parameter values, nosotros acknowledge that border anticipation rates for the 1990's are not based on as well-developed data sources as estimates for more recent years. Thus it remains a possibility that these rates are higher than we believe. One attribute of this incertitude concerns deterrence. When deterrence is higher border crossings will autumn. Most researchers believe deterrence has increased in recent years [8, 12]. We note that reference [12] estimates that the probability of eventual entry after multiple attempts on a single trip in the 1990s is shut to one, indicating almost no deterrence in the before menses. 1 piece of evidence in support of this is information on the voluntary return rate, which refers to the percentage of individuals apprehended at the border who are released dorsum to their dwelling country without going through formal removal proceedings and not being subjected to further penalties. Voluntary returns are thus not "punished" and thus are less likely to be deterred from trying to cross the edge in the futurity, compared with individuals who are subjected to stronger penalties. The voluntary return rate has fallen in recent years, from 98% between 2000 and 2004 to 84% betwixt 2005 and 2010. Thus, at least based on this measure deterrence efforts have increased. Nevertheless, this does not conclusively demonstrate that deterrence was lower in earlier years and information technology remains a possibility that information technology was higher, which would tend to reduce our estimates of the number of undocumented immigrants. In conclusion we notation that although there is much uncertainty about the border apprehension rate, it would take to be very loftier, above 60% for earlier years, in order to generate estimates of the 2015 population of undocumented immigrants in the range of the current widely accustomed estimate of only over 11 million (this is based on analyzing our model using the conservative gauge values for all other parameters). This seems implausible based on our reading of the literature.

Population outflows

Population outflows are cleaved into four categories: (I) voluntary emigration; (Ii) bloodshed; (III) deportation; and (IV) modify of status from unauthorized to lawful.

(I) Voluntary emigration rates are the largest source of outflow and the most uncertain based on limited data availability. It is well accustomed that voluntary emigration rates pass up sharply with fourth dimension spent in the country [xvi]; thus we apply dissever emigration rates for those who take spent one yr or less in the U.S., two-10 years, or longer. Nosotros use the following values for our bourgeois estimate. Offset, for those who have spent i year or less we presume a voluntary emigration rate of 40%. This approximate is based on data for the first-year visa overstay exit rate (the fraction of overstayers who left the state within ane twelvemonth from the day their visa expired) for 2016 [17], which is in the lower thirty percent range (the rate for 2015 is like). We note that the rate for visa overstayers is very likely a substantial overestimate for illegal border crossers, who are widely viewed equally having a lower likelihood of exiting in the first year, peculiarly in more recent years [12]. The 40% first-twelvemonth emigration rate that we assume is well above the standard values in the literature [4, 12, sixteen, 18], which range from 1% to 25%. Hence this assumption contributes to making our gauge of the number of undocumented immigrants in the country a conservative ane. For years two-10 we assume a rate of 4% per year. This is the upper bound amongst estimates in the literature, which prevarication between 0.01 to 0.04 [4, 16, 18]. Lastly, for years 10 and in a higher place, published estimates of the emigration rate typically autumn effectually one%; nosotros set this rate to 1% per twelvemonth in line with these estimates. Annotation that given the extremely high 40% emigration rate that we assume for those who accept only been in the country for i year or less, overall annual emigration rates in our model simulation are significantly higher than those plant in the literature or government sources. To further enhance the conservatism of our model, we assume that all undocumented immigrants present at the offset of 1990 accept been here for simply 1 year.

For our simulation analysis we dissever commencement-year voluntary emigration into ii categories, visa overstayers and illegal border crossers. For visa overstayers we assume the first-year charge per unit falls in the range [.25,.50] (uniform) for each year; based on the discussion in the preceding paragraph and literature cited in that location, this is a relatively bourgeois range with midpoint 37.5% to a higher place nearly all accepted estimates. For illegal border crossers there is information indicating that first-yr voluntary emigration rates vary across cohorts [12] (we are not enlightened of such data for visa overstayers). To incorporate this, we assume that a voluntary emigration rate is drawn for each cohort yr from a uniform distribution that is specific to that cohort's twelvemonth of initial entry; the lower bound of this range is gear up past the numbers in [12] and the upper bound is set at 0.50. Again our assumptions here are bourgeois, since we use an accustomed value in the literature every bit our lower jump and permit emigration rates to range to very high values. For years ii-10 and ten and above we use the same distributions for overstayers and illegal edge crossers. For years 2-10 we draw a value from the range [.01, .05], for which the mean value of three% is relatively high and thus conservative; and for years ten and in a higher place we draw a value from the range [.005,.02], thus centered slightly above the standard value in the literature. We annotation that the beginning-year rate is the most critical for our analysis.

An important issue is round flow of migrants, which refers to individuals who enter the country, then exit temporarily and re-enter a short time later. In that location is limited numerical information for round menses rates. However, it is logical and recognized in the literature [12] that when border anticipation rates are higher round flow rates for border crossers tend to diminish: Given information technology volition be more difficult to re-enter the country successfully later, illegal edge crossers in the country will tend non to get out for temporary reasons. Thus this issue is important for illegal border crossers (just not likely to exist equally relevant for visa overstayers). Thus in our simulation we impose a negative correlation between the beginning-year emigration rate and the edge apprehension rate for illegal border crossers; based on our own analysis for annual data from the best contempo report [12] nosotros use a correlation of -0.5 (come across the Supporting Data for details). Nosotros note that this correlation does not substantially change the range or mean of our simulation results, but does reduce the variance.

(2) The mortality rate applied is the historic period-adjusted mortality charge per unit reported by the Centers for Illness Command and Prevention [xix]. For our conservative estimate nosotros set this value at 0.vii percentage, and for the simulation we draw a value from the range [0.5,1.0] pct. Nosotros view these values as conservative. Experts in the field argue that this rate overestimates mortality among undocumented immigrants [iv]. To further bank check that our bloodshed rate assumptions are an overestimate and thus contribute to making our overall estimate of the number of undocumented immigrants conservative, nosotros combined the age, gender, and country of birth distributions of undocumented immigrants reported in [2, 20] with CDC mortality rates [19]. The resulting mortality rate is much lower than the mortality rate we assume (meet the Supporting Information for details). We note that the bloodshed rate is low relative to the voluntary emigration rate, and thus a less of import parameter for the calculation we make.

Lastly, (3) the annual number of deportations is taken directly from DHS annual statistics [xi, 21] for each year. (IV) The number of undocumented immigrants who change to legal status in each year is also taken directly from published information [4, 11]. We include the number of deferred action for babyhood arrivals (DACA) recipients as population outflows even though such individuals remain technically undocumented, which over again serves to underestimate the size of the population.

Simulation methodology

Our simulation is designed to evaluate the range of outcomes the model produces, thus taking into account important sources of variability. There are two main sources of dubiousness: parameter dubiousness, and inherent population variability conditional upon a prepare of parameter values. We take both sources into account, but note that the start source is the main cistron contributing to the variability of the population distribution in the model.

We accost parameter uncertainty past establishing ranges for key parameters. As documented above, these key parameters are (i) the visa overstay charge per unit; (ii) the border apprehension rate for individuals attempting to cantankerous the edge illegally; (iii) the voluntary emigration charge per unit, which is set separately for illegal border crossers and visa overstayers for the beginning year and then jointly for years ii-10 and years 10 and above, and for which we institute a cohort-specific range for each annual cohort for the commencement-year rate for illegal border crossers; and (iv) the mortality rate. For each parameter, we establish a uniform distribution over the gear up range (and impose a negative correlation between the border apprehension rate and start-yr voluntary emigration rate for illegal border crossers). Then, in each simulation run nosotros sample a value for each parameter from its underlying distribution. All of the ranges for the parameter distributions have been specified in the preceding sections. We likewise sample a value for the initial population of undocumented immigrants in 1990 from a Poisson distribution with a mean of iii.5 one thousand thousand, the about widely accustomed estimate of the population of undocumented immigrants every bit of that date. Come across the Supporting Information for further details.

To model inherent population uncertainty given a set of parameter values, nosotros impose a Poisson construction on our model. Specifically, the population in a detail year, provisional on a set of parameter values, is represented equally the sum of all individuals who accept entered the land in previous years and take remained in the country from their year of inflow until the particular year in question. The number of entries (in Poisson terminology, arrivals) in whatever yr is drawn from a Poisson distribution with hateful dependent upon the underlying parameter values governing anticipation probabilities and visa overstays for that year, while the probability that a new immigrant remains in the country from entry until the item year in question is determined based on the parameters governing voluntary emigration, mortality, displacement and change-of-condition rates. It follows (see the Supporting Information for mathematical details) that the number of individuals who enter the land in any given year and are nonetheless in the land at some futurity appointment will likewise follow a Poisson distribution. Further, the number of individuals who enter in any given twelvemonth and remain in the country at a hereafter time can be considered to exist statistically independent given the underlying parameter values (see the Supporting Information for details). Thus, the population of undocumented immigrants in a particular year, which is the sum of those who accept entered in by years and are nevertheless in the land in the detail year in question, also follows a Poisson distribution, for the sum of independent Poisson random variables is itself Poisson distributed.

We ran one,000,000 trials simulating the model. For each trial we recorded the full number of undocumented immigrants predicted to be in the U.S. in each year from 1990 through 2016 for that trial.

Following suggestions fabricated by the Bookish Editor based on comments fabricated by a reviewer, we performed an additional set of simulations making fifty-fifty more than bourgeois assumptions about net inflows over the period 1990-98. This is the menstruation for which there is significant uncertainty about internet inflows of undocumented immigrants. Specifically, we calibrated the model such that the net inflows are half a million per year over this menstruation (in line with the residual method's estimates during this period) and computed the pooled number of undocumented immigrants at the terminate of 1998 based on this approach. We and then fake our model forward from that point using the same framework described above.

Results

Fig 1 depicts our results for twelvemonth 2016, the most recent year for which we are able to produce an gauge. The graph depicts the relative frequency of the number of undocumented immigrants in the U.Southward.; information technology is a smoothed version of the histogram we generate based on simulating our model 1,000,000 times. The effigy as well shows our conservative estimate of 16.7 million in Red, and the nigh widely accepted estimate heretofore of 11.3 meg in Blue on the far left. We notation that this terminal gauge is for 2015, simply should be comparable since both the estimates based on the survey approach and our modeling approach bespeak that the number of undocumented immigrants has remained relatively abiding in recent years. Finally, the mean estimate of 22.1 million is shown in black in the centre of the distribution. Information technology is clear from the Figure that based on the data we use, our assumptions, and our demographic model, the currently accepted estimate falls outside the range of likely values. And our conservative guess is indeed conservative based on our modeling approach and parameter ranges, lying at approximately the 2.fifth percentile of the probability distribution.

Fig 2 displays our simulation results for each year from 1990 through 2016. Our conservative estimate of the number of undocumented immigrants for each yr is shown in Red, the well-nigh widely accustomed guess (through 2015) is shown in Blueish, and the hateful value nosotros estimate for each year is shown in Black. The results show that our model estimates follow a similar shaped trajectory as the widely accustomed current estimates do, but grow faster and are well in a higher place those estimates for every year.

Fig 2. The current widely accustomed estimate of the number of undocumented immigrants in the U.S. (in Blue); together with our conservative estimate (in Red); and the mean value nosotros gauge for each year (in Blackness).

https://doi.org/10.1371/journal.pone.0201193.g002

The results of our analysis are articulate: The number of undocumented immigrants in the United States is estimated to be substantially larger than has been appreciated at to the lowest degree in widely accepted previous estimates. Even an estimate based on what nosotros view as conservative assumptions, in some cases unrealistically so, generates an guess of 16.7 million, well above the conventional gauge of 11.3 million. The mean of our simulations, which range over more standard but still conservative parameter values, is 22.1 million, essentially twice the current widely accustomed estimate; the ninety-five percent probability interval is [16.2,29.5].

Fifty-fifty for the scenario presuming net inflows of 0.v meg per year for 1990-98 our results nonetheless exceed the electric current estimates substantially. The hateful approximate is 17.0 million with a 95% probability interval of 13.5 million to 21.1 1000000. The conservative estimate for this scenario is xiv.0 million, however significantly above the widely accepted guess of 11.3 meg.

Give-and-take

It is currently adequately widely accepted that there are approximately 11 1000000 undocumented immigrants in the The states. This guess, derived from population surveys and legal immigration records, has formed the backdrop for the clearing policy argue in the United States. Using a different approach grounded in operational data, and demographic and mathematical modeling, we take arrived at college estimates of the undocumented immigrant population.

A possible explanation for the discrepancy in these results is that the survey-based arroyo taken in [2–4] must surmount two challenges. Start, information technology requires reaching a representative sample of all those born outside of the United States. 2d, it requires accurate responses from survey respondents when asked where they were born, and whether they are American citizens. Information technology is plausible that undocumented immigrants are more than hard to locate (and survey) than other foreign-born residents of the United States, and if contacted, undocumented immigrants might misreport their state of origin, citizenship, and/or number of household residents fearing the possible consequences of revealing their true status. Whatsoever of these circumstances would lead to underestimating the truthful number of undocumented immigrants.

Our approach, summarized above and detailed in the Supporting Information, is grounded in central principles of demographic flows. The size of any population can be represented as its initial value plus cumulative inflows minus cumulative outflows. We have specialized this approach to the number of undocumented immigrants in the United States, and have drawn upon previously unavailable data. From border apprehensions and visa overstays, it is possible to infer the number of new undocumented arrivals past reversing the flow: how many new arrivals are necessary in order to meet the number of apprehensions and visa overstayers observed? Similarly, consideration of deportations, voluntary emigration, mortality and change-of-condition enables 1 to infer the duration of stay in the country from the time of arrival. Together, this logic enables reconstructing the inflow and departure processes governing population inflows and outflows that issue in the population of undocumented immigrants in the land.

In developing estimates we accept attempted to utilize parameter values that understate inflows and overstate outflows. Our results are most sensitive to the assumptions we make about the probability of border apprehension and the voluntary emigration rates of undocumented immigrants leaving the U.s.. Further research could explore in greater detail the affect of assumptions about these parameters on estimates of the number of undocumented immigrants. To explore the doubt of our estimates we have conducted extension simulations over parameters, simulating 1 one thousand thousand different population trajectories; further inquiry could widen the ranges of parameters and consider boosted parameter incertitude. Further research could also analyze inflows and outflows based on country of origin.

Our results lead us to the determination that the widely accepted judge of eleven.3 1000000 undocumented immigrants in the U.s. is also small. Our model estimates signal that the true number is likely to be larger, with an estimated ninety-five percent probability interval ranging from sixteen.two to 29.v meg undocumented immigrants.

Supporting information

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