Washington — In recent decades, every state has seen a dramatic increase in the share of its population convicted of a felony, leaving more people facing hurdles in finding a job and a place to live and prompting some states to revisit how they classify crimes.

In Georgia, 15 percent of the adult population was a felon in 2010, up from around 4 percent in 1980. The rate was above 10 percent in Florida, Indiana, Louisiana and Texas.

Less than 5 percent of the population in Maine, Nebraska, New York, Utah and West Virginia were felons, but every state had a large increase between 1980 and 2010, when the felony population ranged from 1 to 5 percent, according to a University of Georgia study published in October.

New Hampshire had a low increase, to 3.89 percent in 2010 from 2.56 percent in 1980. Vermont was higher: 7.22 percent of the adult population was a felon in 2010, up from 2.68 percent in 1980.

The new estimates only go through 2010, before many states began to reclassify some crimes, scale back sentencing and take other steps to lower incarceration rates and ease ex-offenders back into society. But they are the first attempt to gauge the state-by-state buildup of felons during a nationwide, decadeslong surge in punishment: Less than 2 million people were in prison or jail or on parole or probation in 1980, compared with more than 7 million in 2007.

John Pfaff, a law professor at Fordham University, called the study “incredibly important,” but noted that with many gaps in information provided by states, further study may be needed to ensure an accurate picture. Nonetheless, he said, some of the state differences make intuitive sense.

“Georgia has been trying to get people out of prison with probation, but we’re seeing that even with probation they’re still getting that record,” Pfaff said. It’s possible that in states with relatively small black populations like West Virginia and New Hampshire, “without that racial divide between a white correctional system and a poor black population, it may be no coincidence that there’s a lower felony rate,” he said.

Proponents of more lenient sentencing tend to focus on imprisonment, where Louisiana and Oklahoma have the highest rates, but probation is more common.

There were 1.9 million people on felony probation in 2015, compared to 1.5 million in prison. In 2010, the two figures were about the same, at 1.6 million, according to the latest federal statistics.

Many view probation as a more humane alternative to imprisonment, said Michelle Phelps, an assistant professor of sociology at the University of Minnesota. But in some states probation has become a “net widener” that draws more nonviolent criminals into the stigma and harsh supervision of a felony conviction.

Several states have moved in recent years to ease the path for convicted felons, including restoring voting rights and prohibiting employers from asking job applicants if they have a criminal record.