This Washington Times story describes the outcry of Congressmen over the greater than usual gridlock in the District of Columbia resulting from "Tractor Man's" occupation of the D.C. mall on a tractor. One congressman said "if a fender bender ... or a guy riding a tractor having a bad day can bring us to a stop, imagine what a terrorist can do."
Still unknown to me is the route Tractor Man took to get into the City - I can't imagine a tractor getting far on any of the main roads without being apprehended before it reached the Mall. (I never saw a tractor on the Roosevelt Bridge during my time in the City.) Also, around here, seeing a tobacco farmer on a tractor is not the worst thing, although they are becoming increasingly rare as tobacco subsidies wane.