U.S. nuclear weapons are now positioned in 16 states - nine fewer than just three years ago when major cutbacks in the arsenal began, according to private nuclear specialists who have tracked the weapons for a decade.

North Dakota has replaced South Carolina as the state with the most nuclear warheads, and Louisiana’s Barksdale Air Force Base is now the single largest U.S. nuclear arms site, a report by Robert Norris and William Arkin said.

The nine states that have become nuclear weapon-free since 1992 are Alaska, Arkansas, Florida, Hawaii, Kansas, Maine, Michigan, New Jersey and New York, they said.

At the peak in the 1980s, there were roughly 24,000 U.S. nuclear warheads around the world. Now there are about 9,000, and by the turn of the century the total will be about half that if strategic arms reductions treaties are implemented.