Crime rates have dropped substantially in the United States, but incarceration rates have remained high. The standard explanation for the lasting trend in incarceration is that the sentencing policy choices from the 1980s and 1990s permanently increased punitiveness: i.e. a long-standing period effect. Our paper examines an alternative explanation that the crime waves in the 1980s and 1990s created cohort differences in incarceration over the life course that changed the level of incarceration even decades after the crime wave. With individual level longitudinal sentencing data from 1972 to 2016 in North Carolina, we find clear evidence that period effects played a relatively minor role in comparison to cohort effects in the secular trends in incarceration. The birth cohorts that reach prime age of crime during the 1990s crime wave have elevated rates of incarceration throughout their observed life course. The key mechanism for their elevated incarceration rates decades after the crime wave is the accumulation of extended criminal history under a sentencing structure that systematically escalates punishment for those with priors.