The crime rate in the United States was rising for 20 years until it reached its peak in 1991. From that point crime in the U.S. has steadily declined.
The most prominent and successful theory explaining this pattern came from Steven Levitt. He showed that we finally saw the effects of legalized abortion that had begun 20 years earlier in the 1970s that reduced the number of unwanted children, the future criminals.
Crime is related to three factors. (1) The number of people aged 12 to 25. That is because crime is a juvenile behavior, (2) The certainty the criminal will be caught and (3) The certainty of being punished. These are traditional points in criminology.
What most people are not aware of, because movies and TV shows always focused on the successful collection of fingerprints in identifying criminals, is that fingerprints were insignificant before 1981. There was no national fingerprint database because we didn't have adequate computers.
Before 1981 the typical big city fingerprint file was 5000 hard-to-read original pages of local criminal prints. After 1981 the FBI and others created a multimillion fingerprint national database for local use.
I contend that this significantly increased the likelihood that a criminal would be (point 2) caught and (point 3) punished. The new national fingerprint database resulted in reducing the amount of crime as more criminals were caught and put in prison.
I personally observed several unsolved murder cases committed in the late 70s that were finally resolved and brought to justice after the original fingerprinting finally became useful in 1981.
Just something to add to your knowledge base.