I live in Alexandria, VA - just outside D.C. I am very fortunate to have a dog park within walking distance. It's just a fenced in area the size of half a football field, but she has some good buddies there
We also have a more elaborate park about 10 minutes' drive from here - there is more room to run and chase (and I get some running in myself!), PLUS it's built next to a creek where the doggies can swim. We had a few warm days last week and she went swimming for the first time - I was so proud!