The age of sexual consent for males in DC is 16. (It's 18 for females.)
And there's no age difference provision? Some states have laws that differentiate, so that a 19 year old with a 15 year old (who could be a fellow high school student, or was the previous year) wouldn't qualify as statutory rape, but an older man with a 15 year old girl would. That's a sensible approach IMO.