The Justice Department says four-point-four percent of prison inmates and three-point-one percent of jail inmates reported one or more sexual assaults between 2008 and 2009.
Of the incidents reported, more of the assaults involved prison or jail staff.
Male inmates were more likely to have sex with staffers than women prisoners.
However, women were twice as likely to report being attacked by another inmate.
The survey identified eight men's prisons, two women's prisons, and six jails as high-rate facilities based on the number of inmate-on-inmate sexual assault.