WASHINGTON — Fanned by the financial crisis, a wave of sentencing and parole reforms is gaining force as it sweeps across the United States, reversing a trend of “tough on crime” policies that lasted for decades and drove the nation’s incarceration rate to the highest — and most costly — level in the developed world.

While liberals have long complained that harsh mandatory minimum sentences for nonviolent offenses like drug possession are unjust, the push to overhaul penal policies has been increasingly embraced by elected officials in some of the most conservative states in the country. And for a different reason: to save money.