Crime rates in the U.S. have fallen by about half since the early 1990s. A new working paper from the National Bureau of Economic Research finds that legalized abortion following the Supreme Court’s landmark Roe v. Wade decision in 1973 accounts for 45% of the decline in crime rates over the past two/three decades.

“…Donohue and Levitt (2001) presented evidence that the legalization of abortion in the early 1970s played an important role in the crime drop of the 1990s. That paper concluded with a strong out-of-sample prediction regarding the next two decades: “When a steady state is reached roughly twenty years from now, the impact of abortion will be roughly twice as great as the impact felt so far. Our results suggest that all else equal, legalized abortion will account for persistent declines of 1 percent a year in crime over the next two decades.” Estimating parallel specifications to the original paper, but using the seventeen years of data generated after that paper was written, we find strong support for the prediction. The estimated coefficient on legalized abortion is actually larger in the latter period than it was in the initial dataset in almost all specifications. 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. …”

Here is the NBER link, to paper and a backround on the debates are it here: https://journalistsresource.org/studies/economics/abortion-crime-research-donohue-levitt/