Nogales is a tough area. We spent our honeymoon in AZ and visited family that I hadn't met yet. At the time they lived appx. within 50 miles of the Nogales/AZ border. We had a rental car and drove around, took a wrong turn and wound up in Nogales. We were spotted and the Mexicans came out of the pool hall with cue sticks in hand wanting to see the gringos who dared come near. It was a rather alarming experience. Obviously we turned around quickly and headed back.
Things have only gotten much, much worse.
Until Mexico solves it's own problems and the U.S. draws a line and closes it's borders and deals with the drug cartel and our politicians who are profiting, things will never change.