Mt Vernon. Clay. But the previous homeowner obviously amended two large flower beds, because the soil there is fantastic! I am working on the third.

NE DC near the Ft. Totten Metro--a strange mix of sand and clay. Pure red clay in some places, almost pure sand in other places. The weird thing is that in a lot of the yard, it's a layer of clay, and if I dig down about a foot it's sand underneath. We've amended it a lot. If you mix the pure clay and pure sand, it will harden into a cement like substance when it dries.