How old do you have to be to get into bars in D.C.?

i'll be living in D.C. next semester for an internship. i'm only 20, and i won't be 21 until the end of the semester. i live in Indianapolis and HATE it because there's nothing to do except go to bars and you're not allowed into bars at all unless you're 21 in Indy. all of my friends are older than me so they can go out but i can't. will i be able to at least go out with them if i can't drink or will i be in the same situation some 400 miles away?