FBI statistics released Monday show that 187 forcible rapes were reported in the District last year, up from 150 in 2009. That's a sharp contrast to the 5.5. percent decline nationwide.
No state had a larger increase in reported rapes than the District, according to the FBI data. Individual data for other cities was not available, but cities with populations between 500,000 and 1 million overall showed a 4 percent drop in forcible rapes.
D.C. police union chief Kris Baumann said the department hasn't done enough to curb the number of rapes.
"Particularly when talking about a crime like rape, where public awareness and vigilant, proactive enforcement in the case of a sexual predator can make a real difference, the fact that this department did nothing to warn the public and did nothing to combat this problem is inexcusable," he said.
Gwendolyn Crump, a D.C. police spokeswoman,wrote in an email that the department conducts outreach "to empower victims and encourage them to report offenses." D.C. police also work with local colleges and universities, she said.
Crump also noted that domestic violence is a factor in many rape cases, and the District's 2010 numbers are "consistent" with figures from 2006, 2007 and 2008.
But the true number of victims is likely even higher, advocates for victims of sexual violence say.
The National Sexual Violence Resource Center estimates that more than half of rape victims don't report the incident to police.
"You have a huge chunk of people who aren't being counted," said Tracy Cox, the center's communications director.
Cox said part of the reason for the increase in D.C. rapes could be that more victims filed reports.
The number of reported rapes rose 6.1 percent in Maryland and declined 2.5 percent in Virginia.
The District saw a slight drop in violent crime overall: a decline of 1.1 percent, compared to a nationwide decline of 6 percent. And the city saw a small uptick in property crimes -- a 0.6 percent increase -- while the nation experienced a 2.7 percent decline.
All violent crimes except rape declined last year. Among property offenses, burglaries saw the largest rise, with a 14.5 percent jump.
Baumann said that rise was concerning because "burglaries are the type of crime where things can go very, very badly" and lead to more violence.
Crump said burglary "has been a problem this year" and police officials have increased patrols, encouraged people to set up burglar alarms, lock doors and report suspicious activity.
Cynthia Lum, a criminology professor at George Mason University, said it's hard to pinpoint why crime drops in one area and increases in another.
"The more important question that the police department must ask itself is 'are we doing everything we can possibly do to increase safety and reduce violence in our city?'" she wrote in an email. Strategies like proactively targeting high-crime spots are particularly effective, she said.