I don’t think there’s any legal way to ban an American citizen from visiting any city in the country they want since freedom of movement is a fundamental Constitutional right under U.S. law. For that matter the First Amendment can make it tricky to stop an individual from holding a political rally (they can require a permit, but can’t deny one just because the candidate involved is an asshole). So if he’s hellbent on going to Springfield it’s going to be hard to stop him from both a legal and political standpoint.
That said the local government clearly doesn’t want him there. The Republican Mayor has basically been begging Trump “please cut it out with the racist lies and for the love of all that is good and holy please don’t come here.” But the leopards are hungry…
