The answer was no everywhere. I was in D.C., and thanks to conferences and freshman orientation for Congress, there were no hotel rooms in the city. (People were even taking cabs to Baltimore!) With occupancy way up this year, it's a situation that's become all too common.
So what can you do? Start with hotels where you are a preferred loyalty-program member, and ask for the front desk directly (never talk to central reservations). If you fail, ask them where else to call. (When cities book up, hotels call one another to help place extra guests.)
It's always good to call around noon or 4 p.m., as that's when guests check out early or don't show up. If you're with a big company, press your travel agent to find out if your firm has blocks of rooms on reserve. As for me? After a night on a friend's couch, I finally convinced the Hotel Rouge to give me a room.