Campgrounds near Washington D.C.?

We are looking to do a couple of nights somewhere and sightsee DC during day. Do not want to drive longer than 30 minutes.
Thanks


As mentioned, at Cherry Hill, the only driving will be from your campsite to the campground parking lot next to the campground Metro bus terminal... not a bad deal! :C

Also as mentioned, take the daily 4pm travel class at the campground community room, found it to be very informative.

Mike