We estimate that crime fell roughly 20% between 1997 and 2014 due to legalized abortion. The cumulative impact of legalized abortion on crime is roughly 45%, accounting for a very substantial portion of the roughly 50-55% overall decline from the peak of crime in the early 1990s.
Roe vs Wade:
1973
This was the research done by Freakonomics!
Podcast revisiting this research with sources at the bottom:
https://freakonomics.com/podcast/abortion-and-crime-revisited/
This is the revisited research paper showing the connection (PDF):
https://bfi.uchicago.edu/wp-content/uploads/BFI_WP_201975.pdf