Prison Population in U.S. Federal Penitentiaries: Americans vs. Illegal Aliens Number of People in the U.S. Federal Penitentiaries as of 30 March 2019: 179,761 By population ratio, there are 27 times the number illegal aliens in Federal Prisons who committed heinous crimes compared to Americans. If the quoted number of 11M illegals in the US were used, the crime ratio would be a lot worse at 31 times more illegals.  NOTE: The 11M illegal alien count is literally a 20 year old out dated figure. Current studies from Yale & MIT show there are actually 22 million illegals. For the updated number of illegals in the US, see this Yale/MIT study:  https://thehill.com/latino/407848-yale-mit-study-22-million-not-11-million-undocumented-immigrants-in-us https://thehill.com/opinion/immigration/413294-prior-estimates-of-undocumented-immigrants-in-us-were-way-off