Violent crime plummeted throughout the 90s because abortions was legalized in 1973, 17-27 years before 1990 and 2000, respectively, roughly coinciding with the early adulthood period where a vast majority of criminal offenses are committed, the offender having the freedom of an adult without the fully formed prefrontal cortex of one yet.

The fetuses that were aborted were overwhelmingly from socioeconomic demographics (e.g. poverty, single mother households) where they would've been statistically far more likely to become criminals, so by allowing that generation to be aborted, we effectively aborted (for the first time) a large chunk of an entire generation of people that would've been statistically overrepresented among criminals, entering their peak criminal years right when Bill Clinton was president.