Most live in heavily populated areas, meaning more people to vote in one location.
Not really, all things being equal it would depends on how large precincts are and how many machines are dedicated to a precinct as well as voter turn out. Also the type of ballots being used, punch cards and paper ballots slower than mechanical or electronic machines.
In urban areas blacks generally have a large degree of control in elections, in NO our sheriff and registrar are black, the commissioner of elections is white, most of the board is black. It is illogical to assume the blacks in power are creating adverse conditons in black precincts.
Do blacks take longer in the machines, at the punch cards, filling out ballots? Do they have more problems presenting ID's and signing the rolls, do they chit chat longer with the election workers, are they more likely not to know how to open the curtain and just walk out with oot completing the process? yes, yes, yes, yes