Parents in Prison
"An estimated 809,800 prisoners of the 1,518,535 held in the nation's prisons at midyear 2007 were parents of minor children, or children under age 18. Parents held in the nation's prisons -- 52% of state inmates and 63% of federal inmates -- reported having an estimated 1,706,600 minor children, accounting for 2.3% of the U.S. resident population under age 18."
Glaze, Lauren E. and Maruschak, Laura M., "Parents in Prison and Their Minor Children" (Washington, DC: US Dept. of Justice Bureau of Justice Statistics, Aug. 2008), NCJ222984, p. 1.