Last time around a friend was in it, so I watched a bit and was amazed by the huge mass of people running down Harvard Street -- pretty impressive. About the closest I've ever come is a 1/26 marathon at a very slow pace. I wrote about it too, definitely worth checking out.
But anyway, there are going to be a number of road closures in our area. The full list is here, but here are the ones that will most affect us, and when: Columbia Rd NW from Adams Mill to Harvard from 7-11 AM and Harvard St NW from Columbia to 5th from 7-11:30 AM (plus some around Howard.)
They also made this handy map of the closings:
View 2013 Rock ‘n’ Roll USA Marathon & CareFirst Rock ‘n’ Roll USA Half Marathon in a larger map