We provide the first nationally representative long-run series (1870–2020) of incarceration rates for immigrants and the US-born. As a group, immigrants have had lower incarceration rates than the US-born for 150 years. Moreover, relative to the US-born, immigrants’ incarceration rates have declined since 1960: immigrants today are 60 percent less likely to be incarcerated (30 percent relative to US-born Whites). This relative decline occurred among immigrants from all regions and cannot be explained by changes in observable characteristics or immigration policy. Instead, the decline is part of a broader divergence of outcomes between less-educated immigrants and their US-born counterparts.