3/6/19: What Customs and Border Protection Data Says About Illegal Migration and Crime

The Customs and Border Protection, a U.S. agency responsible for border protection, publishes handy stats on its enforcement actions "related to arrests of criminal aliens for Fiscal Years 2016 - 2018, and FY 2019 TD (to date) (October 1, 2018 - April 30, 2019)". Here is a link to the reported data: https://www.cbp.gov/newsroom/stats/cbp-enforcement-statistics/criminal-alien-statistics. A summary of all annual reports available so far is provided in the table below:

Here are some takeaways from the data (subject to many caveats):

1. There is no 'criminals at the border' crisis anywhere in sight. In fact, total number of recorded crimes committed by illegal aliens has dropped from an average 20,047 in 2015-2016 to 7,208 in 2018-2019 (using annualized figure for 2019 to-date). That is a decline of 64 percent. 
2. The reductions in crimes are broadly-based. Homicides and manslaughter crimes dropped 85 percent, although the numbers were extremely small to begin with. The second largest drop between 2015-2016 average and 2018-2019 average was recorded in Burglary, robbery, larceny, theft, fraud category, where the decline was 76 percent. The smallest decline of 57 percent was recorded in illegal entry and re-entry category, numbers of which have declined from 9.614 in 2015 to 3,175 in 2019 (annualized).
3. The reductions did not increase during the Trump Administration crackdown on migration. As the table above shows, largest (in percentage terms) declines took place under the Obama administration in five out of nine categories of crimes, and three largest drops took place during the transitionary period (when Obama policies continued to apply over the longer part of the year). Trump administration can claim the top rate of reductions at most in only one category reductions 'Other' category. In six out of nine categories of crime, Trump administration efforts to reduce migrants-related crime have been responsible for the lowest rates of reductions for any year between 2015 and 2019. 
4. In terms of overall crimes recorded, Obama's 2015-2016 and 'largely Obama's' 2016-2017 fiscal years recorded crime reductions of 33 percent and 32.9 percent respectively. Trump Administration years (2018 and 2019) generated reductions of 22.9 percent and 26.9 percent, respectively - both significantly lower than Obama administration period records.

In summary, no, there is no emergency of crime at the border (at least not in the CBP data), and no, Trump administration's policies and executive orders are not effective at reducing crime beyond the past historical trends. In fact, they are not even sustaining past trends.