About six miles.
There's a problem here in Nebraska, because some years ago the state legislature decided to define precincts by population, not by geographical area.
We have a county here larger than the whole state of Connecticut, that based upon population only, warrants only four precincts. This means some people have to make 120-mile round-trips to vote.
We also have several counties the size of Delaware or Rhode Island, one or two precincts.
The problem was supposed to be fixed, but I dunno if has been yet.
To their credit, the solid stalwart red citizenry of rural Nebraska, despite having to go these tremendous distances, maintain their much-above-national-average voting turnout.