You can do this on a large scale, or a small scale, with even selected neighborhoods isolated from the others lest they reach out and throttle freedom and liberty.(/sarcasm)
Only a feg would suggest that, ie. put a rubber on and you're free to roam within certain limits. This is America, she doesn't have to put up with illegal entrants, she doesn't have to put up with non-suitors anymore than your wife or girlfriend should have to tolerate rape.
Take heart, there are still those who'll protect her.