Within the past two weeks, the Congressional Research Service (CRS) has released a report on "Unaccompanied Children from Central America: Foreign Policy Considerations." The data in this report shows that the 2014 flood of "unaccompanied children" (i.e., illegal immigrants below the age of majority) should have been clearly anticipated based on trends observed during the preceding years.

As the figure below --- taken from this CRS report -- illustrates, beginning in 2012 there was a rapid rise (more than 52 percent) in the number of unaccompanied minors compared to the year below, with almost all of the increase concentrated in illegal minors from Honduras, Guatemala, and El Salvador.

There was a subsequent 59 percent increase during 2013 over 2012, followed by a 77 percent increase in 2014 compared to 2013. The trend line from 2011 through 2013 was unequivocal: 2014 should have been expected to be a record year.

Thus, when the CRS report claims that "in FY2014, there was a sharp increase in the number of unaccompanied alien children (UAC) traveling to the United States... This unexpected surge of children strained U.S. government resources and created a complex crisis with humanitarian implications for the United States and the international community," the increase was neither unusually sharp nor should it have gone "unexpected." Extrapolating the exponential increase pattern during the three previous years would have easily predicted the 2014 "surge."

It is also apparent that deportations of UACs back to these three nations are falling far behind the influx:

"Administration officials maintain that the majority of unaccompanied minors apprehended in the United States will be returned to their home countries... In FY2013, the most recent year for which U.S. government data are available by country, DHS deported 159 unaccompanied children to El Salvador, 661 to Guatemala, and 461 to Honduras, for a total of 1,281. According to the State Department's Unaccompanied Alien Children Monitoring Group, U.S. deportations of unaccompanied minors decreased in FY2014, to a total of 510 for all three countries."

During fiscal years 2013 and 2014, 72,510 UACs arrived in the United States from Honduras, Guatemala, and El Salvador, and only 1,791 were deported -- less than 2.5 percent.

During the first quarter of fiscal year 2015 (which began on October 1, 2014), 6,296 UACs from these three nations were apprehended, suggesting that -- if trends continue -- the FY2015 total will be in the neighborhood of 19,000. Add in another 3,635 UACs from Mexico during Q1 of FY2015, and the composite total of UACs expected during FY2015 from these four nations may top 30,000. While this would represent a substantial decrease from FY2014, the influx would still be about twice the FY2011 level and orders of magnitude above return deportation levels.

The cause of the surge from 2011 to 2014 is also of interest. Some would argue that increasingly poor economic and crime conditions in Honduras, Guatemala, and El Salvador drove the rising tide of UACs rather than, perhaps, the weak public stance taken by the Obama administration towards illegal immigration.

One problem with a heavy emphasis on this socioeconomic "root causes" narrative lies in the economic data itself. For both Honduras and El Salvador, the unemployment rates since 2011 have been low and unchanged, while that of Guatemala has been low and declining. Real per capita GDP in these nations are well below that of the U.S., but the annual growth rates since 2011 have been equal to that of the United States. It is difficult to frame a coherent case that these Central American economies took on any unusually poor characteristics starting in 2012 that would have led to such a large UAC exodus on its own.

Homicide rates in El Salvador have fallen substantially from the mid-1990s peak, and declined since 2011. Rates of all other major crimes (e.g., theft, threats, robbery, and extortion) have also dropped since 2011. Trends for major crimes such as homicide in Honduras and Guatemala also do not, on their own, explain the rising UAC movement into the United States.

The real root cause of the recent UAC influx is apparent: the advertisement of weak illegal immigration policies. There has long been a strong socioeconomic driving force for illegal immigration up from Central America and into the United States across its southern border with Mexico, and these pressures have not substantially changed since 2011. What has changed is the expressed tolerance towards -- and even verging on promotion of -- illegal immigration by the current administration. It is a broken windows theory of illegal immigration that played out in near textbook fashion.