The illegal voting would have been stopped or a least greatly reduced with the implementation of proper voter registration and state IDs. Of course, with the rudimentary technology of the era, falsification of ID documents would have been relatively easier than it is today. However IDs and voter registration would have presented an additional obstacle to border ruffians.
The violence would only have been stopped by the concourse of a national guard, a state police and civil deputies from the state protecting voter, voting locations and the transportation of ballots.