A direct consequence of the recent increases in the U.S. prison population is the concurrent increase in the number of former inmates and recently released inmates living in noninstitutionalized society. Between 1980 and 2000, the U.S. prison population increased fourfold from 300,000 to more than 1.2 million. During the same period, the number of ex-offenders residing in the community increased from 1.8 to 4.3 million. Annually, there are large flows into and out of the state and federal prison systems. For example, in 1999 approximately 550,000 inmates were released from prison, 75 percent being conditionally released into state parole systems. Net of conditional returns to prison, releases in 1999 increased the population of recently released inmates by more than 300,000 people.
Raphael, Steven, Michael A. Stoll, Mark Duggan, and Anne Morrison Piehl. "The Effect of Prison Releases on Regional Crime Rates by Steven Raphael and Michael A. Stoll." Brookings-Wharton Papers on Urban Affairs (2004): 247-255.