State and local prisons and jails routinely report to the federal government on the number of deportable criminal aliens and suspected criminal aliens held in their facilities as part of a program known as the State Criminal Alien Assistance Program (SCAAP). The purpose of the reporting is to receive compensation from the U.S. government for the burden of incarcerating deportable aliens.

The Department of Homeland Security (DHS) takes these reports and eliminates any foreign-born prisoners who are not deportable (either because they are naturalized U.S. citizens or are legal permanent residents and their crime is not serious enough to require deportation). The result allows DHS to correctly distribute SCAAP funds to the state and local detention facilities on a pro rated basis.

The ultimate results are a matter of public knowledge and provide an interesting picture into the greatest concentrations of deportable aliens nationwide. The states that have the most number of these deportable aliens are generally those that have the largest estimated size of the illegal alien population. Below are the ten states with the largest number of prisoners (in prisoner years) and the DHS ranking in 2010 (note that nearly 300,000 prisoners identified in the SCAAP system account for the nearly 100,000 detention years):

StateAlien prisoner yearsDHS rank
California32,4631
Texas11,7582
Florida8,1343
Arizona6,4345
New York4,5956
Illinois3,2304
North Carolina2,7067
Colorado2,300N/A
New Jersey2,5509
Oregon1,547N/A

The order varies, however, when the focus is on the share of the inmate population comprised of these deportable aliens. This share ranking eliminates population size as a factor. Six of the major illegal alien population states still appear on this list, but four DHS unranked states are included, i.e., Oregon, Colorado, Utah, and Massachusetts. The ranking by deportable alien share of the overall prisoner population from the SCAAP reports and the percentage are shown below:

Deportable alien share

California12.7%
Arizona11.6%
Oregon9.2%
Colorado6.6%
Nevada6.2%
New Jersey5.8%
Utah5.8%
Texas5.5%
Massachusetts5.3%
Florida5.2%