I grew up in New York City in the 1960's and 70's. In the 60's it was totally safe for me as a kid to ride my bicycle all through Brooklyn, and my neighborhood was a safe working-to-middle class neighborhood. My mom had no problems with sending me as an 11 year old to ride the subway by myself to get to my aunt's house.
I passed through my old neighborhood 20 years later and remarked that I wouldn't want to be on foot and unarmed there. It had completely changed.
Ditto for my old neighborhood in Dallas. We kids used to walk all over the place. Now, though, the neighborhood is a war zone. I’ll let you guess what the primary difference is between Then and Now.