President Barack Obama said the project would create thousands of jobs
President Barack Obama has announced more than $8bn (£5bn) of federal loan guarantees to begin building the first US nuclear power stations for 30 years.
Two new plants are to be constructed in the state of Georgia by US electricity firm Southern Company.
Mr Obama said the plants would be "safe and clean" and were needed to meet the country's future energy needs.
There have been no new nuclear power plants started in the US since the 1979 accident at Three Mile Island.
The accident was caused by the partial core meltdown of one of the reactors at the site in Pennsylvania, which resulted in a release of radioactive gases into the atmosphere.
While the president said the US had not "broken ground on a ... new nuclear power plant in 30 years", some US nuclear plants only became operational in the 1980s, despite construction beginning years earlier.
This one plant will cut carbon pollution by 16 million tons each year when compared with a similar coal plant - it won't persuade all the environmentalists, but it is an argument that does weigh heavily with some of them
The president said the project would create "thousands of construction jobs over eight years and then hundreds of well-paid jobs" when the facilities become operational.
He added that it was "only the beginning" of efforts to develop a new generation of safe and clean energy-efficient technologies, which would help fight climate change.
The two new reactors will be built at an existing nuclear facility in Georgia.
Southern Company said the work would create about 3,000 construction jobs and 850 people would subsequently be permanently employed when the reactors became operational.
'Meet energy needs'
"On an issue which affects our economy, our security, and the future of our planet, we cannot continue to be mired in the same old debates between left and right, between environmentalists and entrepreneurs," said President Obama.
THREE MILE ISLAND ACCIDENT
Partial core meltdown of one of the two reactors at the site, on 28 March 1979
Caused by a faulty valve which allowed large amounts of reactor coolant to leak
Resulted in radioactive gases being released into the atmosphere
About 140,000 people evacuated from the local area
No fatalities, but dispute remains over long-term health impact
Most significant accident in the history of the US nuclear power industry
The reactor in question remains mothballed, but the other at the site is still in operation
"To meet our growing energy needs and prevent the worst consequences of climate change, we'll need to increase our supply of nuclear power. It's that simple."
Southern's chief executive David Ratcliffe said the president's announcement was "an important endorsement in the role nuclear power must play in diversifying our nation's energy mix and helping to curb greenhouse gas emissions".
There are currently 104 operating nuclear reactors across 31 states in the US, which provide about one-fifth of the country's electricity.
Meanwhile, there are currently 56 new nuclear reactors being built around the world.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.