Small population towns & great distances between them do a lot to keep behavior “neighborly”. In a big city you can give the other guy on the road the finger, for no great cause, & be fairly certain you’ll never see him again. In small towns you know you probably will run into him again, soon, so if you're not stupid you think out your responses to trivial transgressions a little more.
Likewise, criminals don’t have anywhere to blend in & aren’t likely to escape when there is 200 miles of two lane highway to traverse before the next town...
More people = more problems
