The number of Americans in jails and prisons across the country continued to fall in 2015, according to new government statistics, as both violent and property crime rates reach low levels not seen in half a century.

Nationwide, just shy of 2.2 million people were serving in local, state and federal prisons at the end of 2015, according to the Bureau of Justice Statistics. The total prison population fell by 51,000 inmates from the year before, the largest drop since 2009.

The number of inmates held by the federal Bureau of Prisons declined seven percent over the last year, while the number of inmates held by state prison systems declined by nearly two percent. Twenty-nine states showed a drop in prison populations.

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The long-term trends are even more encouraging: Between 2010 and 2015, the nation’s imprisonment rate declined by 8.4 percent, according to an analysis by the Pew Charitable Trusts . Over the same period, 35 states have seen their prison populations decline, and the rate of violent and property crime is down nearly 15 percent.

In the last five years, the rate of incarceration has dropped by more than a quarter in California, and by more than 20 percent in Vermont and Alaska. Thirteen other states, including blue states like Connecticut and Maryland and red states like Texas and South Carolina, have seen imprisonment rates drop by more than 10 percent.

“The numbers are showing that we can have less crime and less incarceration, and that fact is really starting to sink in with voters and elected officials across the political spectrum,” said Adam Gelb, director of Pew’s Public Safety Performance Project.

The National Crime Victimization Survey, conducted by the Bureau of Justice Statistics, showed violent crime rates in 2015 sat at levels just a quarter of what they were in 1993, while the property crime rate stood at less than half what it was at its peak in 1991.

The crime rate is down in 44 states over the last five years. Vermont leads the way, with a 36 percent decline in the number of violent and property crimes reported, while eleven other states have recorded declines or more than 20 percent.

Analysts point to a handful of factors that have succeeded in reducing crime rates: The end of the crack cocaine epidemic that wracked the nation in the 1990s, the increasing proliferation of electronic payments and the corresponding decline in the use of cash, and the rise of anti-theft devices on automobiles.

States have also made strides in reforming the way they handle those who run afoul of the law. States led by Texas, North Carolina and California have placed new emphasis on preventing recidivism, increasing substance abuse treatment as well as alternative corrections programs like community-based housing and counseling for low-level offenders.

States that have made significant reforms in corrections policies have also registered the largest drops in crime rates. In the ten states where the rate of imprisonment dropped the most, the crime rate fell by more than 14 percent over the last five years, according to Pew’s analysis. In the ten states where the imprisonment rate rose, crime rates declined by just over eight percent.

The move to reform criminal justice and corrections policies has attracted bipartisan support, including from wealthy donors on both sides of the political spectrum like George Soros and the conservative billionaire Koch brothers. Together, Soros and the Kochs have pushed criminal justice reforms through a multi-million-dollar program they fund through the American Civil Liberties Union.

Still, the number of Americans under some form of surveillance by state and federal corrections officials remains high. One in 37 adults, about 2.7 percent of the population, is either in jail or on parole, according to the Bureau of Justice Statistics. It is the lowest rate recorded since 1994, though well higher than in most other nations.