"If the legalization of abortion following Roe lowered crime, then I would expect to see a drop in arrest and homicide rates among the 18- and 19-year-olds relative to 21- and 22-year-olds from the before to after period. Figures 4a and 4, however, provide no evidence of a cohort effect. Rates of violent crime arrests are practically identical for the two age groups. What is particularly impressive is the similarity in the violent crime arrest rates prior to 1990, which supports the use of 21- and 22-year-olds as a plausible comparison group. The plot for murder and murder arrest rates point to signiŽ cant period effects as all series begin to rise steeply around 1988 and peak between 1993 and 1994."