Population is also a big factor. If 1% of the population* tends to be criminals, a community of 100 might only have a single criminal; a town of 1000 might have 10, and a city of 1 million would probably have 10,000.
So, if Blanksburg went from 1000 people in 1950 to 100,000 in 2020, it stands to reason that the statistical number of criminals will have also increased in those decades.
Likewise, it's easier in those small communities to keep an eye out & on the statistically fewer criminals over a large metropolis. Or a fairly stagnant locality over those with a high turnover.
It's very informative to read both histories of that era, and fiction from that era. For instance, note the dialogue regarding juvenile delinquency in "Starship Troopers" was published in 1959.
*a number I pulled right out of the air