"'[T]he fight ended 'as soon as [the youths] realized who they were up against'... Still decked out in a blue jumpsuit worn during a Thursday concert in Des Moines, Ia., Presley didn't leave the service station until tempers had cooled. 'Elvis asked: "Is everything settled now?"'... [T]he rock star was later amused at his role in the episode. 'Did you see those guys' faces?'"
There's a plaque there now, marking the spot: Elvis Madison Karate Fight Memorial Plaque.
ADDED: Note that I got Iowa in there. That's all the Iowa I'm doing until caucus time. Don't want to max out on Iowa.