Film Dope

Lisa is entered into a competition when she writes a crowd-pleasing speech about how great America is. But when she arrives in Washington she is appalled to witness government corruption first hand and thus ammends her speech in favour of a damning attack on her country and its politicians.

This episode was met with controversy from the timber company due to a major part of the plotline involving a Timber lobbyist trying to bribe a corrupt congressman to cut down the entirety of Springfield Forest.
The title of this episode is, of course a reference to the movie Mr. Smith Goes To Washington.

See here for more details.