On Monday afternoon some yahoo drove his tractor into a pond on the Mall and claimed he had a bomb. The police closed Constitution Avenue between 15th and 23rd streets NW to protect people from exploding engine parts in case he actually had such a device.

That evening about 6, police were still trying to talk the man out of his tractor cab. (He has since surrendered and been jailed.) Constitution Avenue was closed, and I was trying to circumnavigate those eight blocks to get to the Smithsonian Institution to teach a class. It took me an hour and 35 minutes. Near the Eisenhower Executive Office Building I sat through five light changes and had enough time to listen to an entire Joan Osborne CD, file my nails and make friends with the guy in the next car.

On my way home, Constitution Avenue was still closed, and in my search for an alternate route to Virginia I swear I found a bridge I'd never seen before.

The lesson for terrorists is that they need not go to the trouble of hijacking planes or constructing dirty bombs. They just need a piece of farm machinery strategically placed to bring the nation's capital to a standstill.

I'm sure that somewhere on paper there exists a civil defense or homeland security plan for evacuating the city in case of a real emergency. The tractor siege proved that in reality we'd all be parked on H Street, duct-taping our car windows while other motorists dropped dead from nuclear fallout, carbon monoxide or just plain boredom.