In what some experts say may be the beginning of the end for mass incarceration, the U.S. prison population declined for the third year in a row last year.

In 2012, the prison population shrunk by 1.7% (or 27,770 inmates), according to the Bureau of Justice Statistics (BJS).

The third consecutive yearly drop in prisoner numbers has been the result of fewer crimes and changes in state correctional policies. Many states are now relying more on probation and parole instead of locking people up.

Although the percentage decline might seem small, the fact that it followed decreases in 2011 and 2010 indicated the country is undergoing a “sea change” in criminal justice policy.

“This is the beginning of the end of mass incarceration,” Natasha Frost, associate dean of Northeastern University’s school of criminology and criminal justice, told The New York Times.

Before 2010, the U.S. prison population increased every year for 30 years, from 307,276 in 1978 to a high of 1,615,487 in 2009.

The decline has not affected federal prisons, which are seeing record numbers of prisoners.

At least 17 states are selling or are considering selling some of their underutilized prisons. For example, in Pennsylvania, the state is looking to sell off two prisons that were recently emptied and shut down. A 40-building prison in Cambria County and a 32-building correctional facility in Westmoreland County are among 37 surplus state properties listed for sale.

According to BJS, 47% of prisoners have been incarcerated for non-violent crimes, such as property offenses, drug offenses and public order offenses.

Louisiana had the highest percentage of its population in prison last year, 893 per 100,000 state residents. In second place was Mississippi (717 per 100,000 state residents), followed by Alabama (650 per 100,000 state residents), Oklahoma (648 per 100,000 state residents), and Texas (601 per 100,000 state residents).

Maine had the lowest imprisonment rate (145 per 100,000 state residents), followed by Minnesota (184 per 100,000 state residents), and Rhode Island (190 per 100,000 state residents).

-Noel Brinkerhoff, David Wallechinsky

To Learn More:

Prison Populations Down For Third Straight Year (by Ted Gest, Crime Report)

U.S. Prison Populations Decline, Reflecting New Approach to Crime (by Erica Goode, New York Times)

Two Closed State Prisons go up for Sale (by Kate Giammarise, Pittsburgh Post-Gazette)