Yeah I am mainly in NW and Northern VA. Billboards are not illegal, but they are just regulated better. I was mainly comparing with Pensilvania, Ohio and a few Midwest states I drive through sometimes.
When I lived in Sacramento, on the Cap City Freeway there was a highly visible, gaudy billboard advertising liposuction, fat belly and all. I always wondered about that one ... there's no way the funds from renting that space justified the terrible light it cast on Sacramento for visitors passing through, and there must be other bidders. Also it's not as though this is the norm, I can't think of any similarly awful billboards in the Sacramento area, and the Cap City Freeway itself has few billboards.