Pew Research Center

Tennessee carried out its first execution since 2009 this month and Nebraska soon may carry out its first since 1997. The two states underscore the fact that while a majority of jurisdictions in the United States have capital punishment on the books, a considerably smaller number of them use it regularly.

Overall, 31 states, the federal government and the U.S. military authorize the death penalty, while 19 states and the District of Columbia do not, according to the Death Penalty Information Center, an information clearinghouse that has been critical of capital punishment. But 11 of the states that allow executions Ė along with the federal government and the U.S. military Ė havenít had one in at least a decade.

Nebraska, in fact, is among seven states that have the death penalty but havenít carried out an execution in at least 15 years. New Hampshire hasnít executed an inmate since 1939; the other states in this category are Kansas (last execution in 1965), Wyoming (1992), Colorado and Oregon (both 1997), and Pennsylvania (1999). Executions have occurred somewhat more recently Ė though still more than a decade ago Ė in California, Montana, Nevada and North Carolina (all in 2006).

The last federal execution also took place more than 15 years ago, in March 2003. While the U.S. military retains its own authority to carry out executions, it hasnít done so since 1961.

All 11 states that have the death penalty but havenít used it in at least a decade have inmates on death row, as do the federal government and U.S. military. The size of these death row populations ranges from just one inmate each in New Hampshire and Wyoming to 744 in California, which has by far the largest death row in the nation.

Californiaís death row has grown by nearly 100 inmates, or 15%, since January 2006, when it carried out its last execution, and by nearly 30% since 2000, according to the NAACP Legal Defense and Educational Fund, which tracks death row populations for all states. The increase reflects the fact that California juries have continued to sentence convicted defendants to death even as executions themselves have been on hold in recent years amid legal and political disputes.

One stark reflection of the longtime suspension of capital punishment in California is that executions now rank behind natural causes and suicide as the third most common cause of death for those on death row there, according to data from the stateís corrections department. Just 15 of the 128 California death row inmates who have died since 1978 were executed.

The federal governmentís death row has also grown substantially since the last federal execution. There are currently 63 federal inmates sentenced to death, up from 26 in January 2003 (just before the federal governmentís most recent execution).

The increases in the number of people on death row in California and at the federal level are notable because they run counter to the national trend. Nationwide, the number of inmates on death row fell 24% between 2000 and 2017, from 3,682 to 2,792, according to the NAACPís figures.

A variety of factors explain this decrease. For one thing, 867 executions were carried out between 2000 and 2017, including 346 in Texas alone, according to a database compiled by the Death Penalty Information Center. Many other death row prisoners have died of other causes. Another 78 were removed from death row between 2000 and 2017 because they were exonerated, whether by acquittal, dropped charges or pardons. And the number of new defendants sentenced to death has declined sharply, from 223 in 2000 to just 39 last year.

Legal and political factors have played a prominent role in several of the states that have the death penalty but have not carried out an execution for 10 years or more. In California, for example, courts struck down the stateís lethal injection protocol in 2006 and the state did not propose a replacement method until years later. In 2016, California voters approved a ballot initiative intended to speed up the death penalty process.

In Nebraska, the state legislature abolished capital punishment in 2015, only for voters to reinstate it at the ballot box in 2016. That has paved the way for the planned execution of Carey Dean Moore, who was convicted of murdering two men in 1979. The execution still may be postponed, however, due to a late court challenge over how the state acquired its lethal injection drugs.

Nebraskaís Catholic governor, Pete Ricketts, is a supporter of capital punishment and has vowed to move forward with executions in the state despite Pope Francisí announcement earlier this month that the Catholic Church would oppose the death penalty in all circumstances.

Correction: A previous version of this post, as well as the map, omitted North Carolina from the list of states that have capital punishment but havenít carried out an execution in more than a decade.