The United States incarcerates a larger share of its population than nearly any other country. Debate spans policing practices, sentencing, pretrial detention, and reentry, with disagreement about what actually produces public safety.
Incarceration rose sharply from the 1970s through the 2000s, driven by longer sentences and mandatory minimums more than by increased crime. It has declined modestly since its peak.
Most people held in local jails have not been convicted; they are awaiting trial, often because they cannot afford bail. This is a distinct system from state and federal prisons.
Research on what reduces crime points to certainty of consequence more than severity, alongside factors such as employment, housing stability, and neighborhood investment. Policing intensity, sentence length, and social conditions all appear in the evidence with contested weights.