Releasing the results of a first-ever 2010 survey of nearly 10,000 women contacted randomly by telephone, the federal agency said 18.3 percent of women had been victims of rape in their lifetimes.
That includes "completed forced penetration, attempted forced penetration, or alcohol/drug facilitated completed penetration," it said in an executive summary of the 113-page report posted on its website (www.cdc.gov).
Just over half of female rape victims (51.1 percent) said they had been targeted by an "intimate partner" -- a current or former partner or spouse -- and 40.8 percent by an acquaintance.
It also found that 1.3 million women had been raped during the year preceding the survey -- a substantially higher number than the 188.380 rapes and sexual assaults cited in a Department of Justice crime survey for 2010.
"This landmark report paints a clear picture of the devastating impact these violent acts have on the lives of millions of Americans," President Barack Obama's heath secretary Kathleen Sebelius said.
In a statement, Sebelius said the findings of the ongoing National Intimate Partner and Sexual Violence Survey would help the Obama administration shape policy to combat domestic violence and sexual abuse.
Scott Berkowitz, president of the Rape, Abuse and Incest National Network, or RAINN, the nation's biggest anti-sexual violence group, said the data on the lifetime risk of rape was "pretty close" to levels seen in other studies.
But he added that "it's hard to know what to make" of the yawning difference in the number of rapes in the CDC report and the Department of Justice survey, which is based on a substantially bigger number of respondents.
"We really need to look into this more," he told AFP.
"But overall, it shows what crime statistics have shown for years -- that this is an enormously violent crime that affects nearly every family in America," he told AFP.
The report also touched upon male rape, finding that one in 71 men -- nearly five percent of all American men -- had been raped in their lifetime, based on responses from more than 7,400 men who participated in the survey.
More than a quarter of them, or 27.8 percent, said they had been raped before they were 10 years old.