Immigrants are undocumented if they have crossed the border illegally or overstayed their visas. There are a lot of places where I can find the total number of undocumented immigrants, but where can I find a study that provides the number of illegal border crossings versus visa overstays?

  • It is worth noting that it is unlikely that any government will have anything better than a guess for these figures. But assuming that's what you are interested in, please tag the appropriate country in your question to make it clear.
    – Joe C
    Feb 24, 2019 at 17:26
  • @1006a You're right, I clarified the question Feb 25, 2019 at 16:15
  • Good edit--that's much clearer.
    – 1006a
    Feb 25, 2019 at 16:54
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    According to most sources, the number of illegal crossings have dropped in recent years, while the number of visa overstays has risen. Are you looking for what the current situation is, or for a certain period of time?
    – Geobits
    Feb 25, 2019 at 17:40
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    Also, are you asking about people currently in the country from each, or the annual rate of each?
    – Bobson
    Feb 25, 2019 at 17:54

3 Answers 3


A 2017 study from the Center for Migration Studies estimates the proprotion of visa overstays was 42% as of 2014 (the latest year they had data for at the time):

In 2014, about 4.5 million US residents, or 42 percent of the total undocumented population, were overstays.

What's more, the trend since 2007 has been that the majority of new incoming illegal immigrants are from overstays versus illegal crossings (they refer to them as EWIs, or entries without inspection):

Before 2007, well over half of all undocumented arrivals were EWIs. In fact, as recently as 2005, EWI arrivals exceeded overstays by about 120,000. The number of EWI arrivals began a steep decline after 2005, falling from 340,000 in 2005 to 140,000 in 2013. Since the crossover in these trends in 2007, the total number of overstays has exceeded EWIs by about 600,000.


The percentage of overstays increased somewhat from 1995 to 2000, stayed steady until 2004, and then increased rapidly from 2005 to 2010 (Figure 3). This occurred because, as we have seen, after 2005 the number of EWIs fell rapidly while overstays remained at roughly the same level. Overstays reached 61 percent of the total in 2010 and continued to rise, reaching about two-thirds (66 percent) of the total in 2014.

So it's hard to tell from this what the current numbers are five years later, but unless the trend has reversed, the current number is likely to be higher than their estimate of 42%.

And of course, the numbers in this paper (or any other paper looking at this) are subject to some wiggle room, chiefly because the government is the main provider of numbers, and they simply don't track this stuff very well at all.

  • 2
    Note for those comparing the similar sounding claims: "In 2014, 42 percent of the total undocumented population, were overstays" and "Overstays accounted for about two-thirds (66 percent) of those who arrived (i.e., joined the undocumented population) in 2014," this is the difference between current population and annual crossings. Also, the 66% figure seems to reflect that many uninspected crossings do not result in successfully joining the population.
    – John
    Feb 25, 2019 at 19:02

This answer is intended to complement and expand on user3163495's answer above. PLOS also published a critical review of the study referenced above . In this response they point out several assumptions the the prior authors made that are not supported by empirical data and consequentially make their claim of an average 22 million undocumented highly speculative.

In the abstract:

Using emigration rates from the binational Mexican Migration Project survey for the illegal border-crosser portion of the unauthorized population, we generate a 2000 unauthorized population estimate of 8.2 million—slightly below Pew and DHS’s estimates—without changing other assumptions in the model. We conclude that this new model’s estimates are highly sensitive to assumptions about emigration, and moreover, that the knowledge base about emigration in the unauthorized population during the 1990s is not well enough developed to support the model underlying their estimates.

  • I'm not going to downvote this, but it would be better if this critique was put in a comment, and your answer was an alternative source Feb 25, 2019 at 17:36
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    @user3163495 - see my comment to your answer - unfortunately the space allotted for comments prevented being able to quote from the critique of the Fazel-Zarandi study.
    – BobE
    Feb 25, 2019 at 18:06
  • Fair enough, it appears the crux of the issue comes down to having faith in the survey-based method or not, which the commentary linked in your answer alludes to: "Researchers often gather information about populations through U.S. Census-based surveys. Our confidence in these survey-based estimates comes from our confidence in Census field operations, as well as the consistency of these estimates with birth and death records as well as gaps in foreign censuses—specifically the Mexican census—left by their populations’ emigration" Feb 25, 2019 at 18:32
  • I read the critical review linked in this answer, and noticed they are basing their model on just Mexican emigration numbers. The fact they are just using one country's emigration data (and not of all countries south of the border) is strange. This would obviously lead to a lesser total immigrant number Feb 25, 2019 at 18:48
  • The reason I posted the comment and answer is to point out that there are competing analysis based on competing models. Whichever you choose to embrace as a final authority is up to the reader. The absence of empirical data (particularly illegal but unapprehended crossings or the reluctance to release actual and up-to-date "counts") drives the use of modeling, otherwise known as speculation. So it seems that your question is answered ("Where can I find ..."), ...**multiple studies**. Which study is more accurate is an entirely different question
    – BobE
    Feb 25, 2019 at 22:28

NPR, AP News, NBC News, and CBS News have each published an article on this in January 2019 (NBC's article was from October 2018).
They generally place visa overstays at around 58-64% of the total number of unauthorized residence in the U.S., that 66% of the total number of immigrants who joined the population in 2014 were from visa overstays, and claim that visa overstays outnumber uninspected crossings for the seventh straight year (alternative claim: that they outnumber uninspected crossings each year since 2007).

Many of these articles seem to be sourced by the CMS report from 2014, which seems to be one of the most current, comprehensive reports on both types of immigration. This report seems to focus more on total immigrants living in the U.S., as opposed to how many come here per year.

This Politico article states that there were 396,579 illegal border crossings in fiscal year 2018, and that there are about 400,000 per year. The Guardian states that illegal border crossings have lately (since at least 2009) ranged from 340,252 to 556,041 per year.

Extrapolating from all of the above information, there would figure to be about 625,000 visa overstays per year.

AP News reports that there were 701,900 visa overstays in fiscal year 2017.

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