Some 30 years ago, volunteers with Bill Clinton’s presidential campaign knocked on Patty Hernandez’s door in Denver.

After years of a near-full blockade on parole, Alabama is now releasing more people. But grants remain low, prisons are overcrowded, and oversight efforts stalled again this year.

In a populous city in southeast Virginia, a Republican sheriff who calls himself “Detain ’Em Dave” faces a race to the right ...