DC: has strong growth controls in MD+VA, it's big enough that traffic becomes a meaningful constraint (Atlanta has this problem now as well), and it has one of

DC: has strong growth controls in MD+VA, it's big enough that traffic becomes a meaningful constraint (Atlanta has this problem now as well), and it has one of the strongest most recession-proof economics in the country, so prices are still high. I'm having trouble finding the list, but I can't think of a single expensive metro area (in the US) that isn't constrained by water, mountains, growth control laws, or all of the above. Rivers are generally not a problem because federal road funding and near-universal car ownership make it easy to distribute growth on both sides of a river. It is a problem when that river is a state boundary as well (which is often).