The nor'easter churning along the East Coast on Saturday is threatening a dangerous mix of heavy snow and fierce winds for millions of Americans -- and could develop into a historic storm for parts of eastern New England, according to forecasters.

Whiteout conditions are expected across the region, and several governors declared states of emergency as they urged residents to stay off roads. There are also warnings of coastal flooding and the possibility of power outages due to downed utility lines.

An aerial view shows snow covering Central Park in New York, on January 29.
An aerial view shows snow covering Central Park in New York, on January 29.
Tayfun Coskun/Anadolu Agency/Getty Images
A person wears goggles while walking through the snow in downtown Boston, Massachusetts, on January 29.
A person wears goggles while walking through the snow in downtown Boston, Massachusetts, on January 29.
Craig F. Walker/The Boston Globe/Getty Images
A worker shields himself from blowing snow in Boston, Massachusetts, on Saturday, January 29.
A worker shields himself from blowing snow in Boston, Massachusetts, on Saturday, January 29.
Scott Eisen/Getty Images
People walk in the snow outside Faneuil Hall, Saturday, in Boston, Massachusetts.
People walk in the snow outside Faneuil Hall, Saturday, in Boston, Massachusetts.
Michael Dwyer/AP
Mike Ratcliffe shovels snow from his driveway in Providence, Rhode Island, on Saturday.
Mike Ratcliffe shovels snow from his driveway in Providence, Rhode Island, on Saturday.
David Goldman/AP
A person snowboards while pulled from a pickup truck in Providence, Rhode Island, on Saturday.
A person snowboards while pulled from a pickup truck in Providence, Rhode Island, on Saturday.
David Goldman/AP
A woman crosses 57th Street during a winter storm that brought more than seven inches of snow and strong wind gusts to New York City, on January 29.
A woman crosses 57th Street during a winter storm that brought more than seven inches of snow and strong wind gusts to New York City, on January 29.
Anthony Behar/Sipa/AP
Hundreds take part in a spontaneous communal snowball fight in Washington Square Park in New York's City's Greenwich Village during a severe winter storm on Saturday, January 29.
Hundreds take part in a spontaneous communal snowball fight in Washington Square Park in New York's City's Greenwich Village during a severe winter storm on Saturday, January 29.
Seth Harrison/The Journal News/USA Today Network
Patrick Lawrence clears his driveway of snow in New Bedford, Massachusetts, on Saturday, January 29.
Patrick Lawrence clears his driveway of snow in New Bedford, Massachusetts, on Saturday, January 29.
Peter Pereira/The Standard-Times/AP
Waves crash on the coast of Scituate, Massachusetts, on Saturday.
Waves crash on the coast of Scituate, Massachusetts, on Saturday.
Joseph Prezioso/AFP/Getty Images
A person cross country skis through New York's Times Square during a snow storm on Saturday.
A person cross country skis through New York's Times Square during a snow storm on Saturday.
Mary Altaffer/AP
A man walks through Harvard Square on Saturday in Cambridge, Massachusetts.
A man walks through Harvard Square on Saturday in Cambridge, Massachusetts.
Adam Glanzman/Getty Images
People shovel outside of the Davis Square MBTA station in Somerville, Massachusetts.
People shovel outside of the Davis Square MBTA station in Somerville, Massachusetts.
Adam Glanzman/Getty Images
Pedestrians and motorists make their way through heavy snow in Times Square in New York on Saturday.
Pedestrians and motorists make their way through heavy snow in Times Square in New York on Saturday.
Ed Jones/AFP/Getty Images
A man carefully walks down snow-covered subway stairs in Brooklyn, New York, on Saturday.
A man carefully walks down snow-covered subway stairs in Brooklyn, New York, on Saturday.
Brittainy Newman/AP
The entrance to Jim's Clam Shack is covered in snow in Falmouth, Massachusetts.
The entrance to Jim's Clam Shack is covered in snow in Falmouth, Massachusetts.
Bill Greene/The Boston Globe/Getty Images
Children play in the snow in Clifton, New Jersey, on Saturday, January 29.
Children play in the snow in Clifton, New Jersey, on Saturday, January 29.
Michael Karas/NorthJersey.com/USA Today Network
A snowplow clears streets in Rehoboth Beach, Delaware, early Saturday, January 29.
A snowplow clears streets in Rehoboth Beach, Delaware, early Saturday, January 29.
Chuck Snyder/USA Today Network
People walk in snowfall on Friday, January 28, in Wilmington, Delaware.
People walk in snowfall on Friday, January 28, in Wilmington, Delaware.
William Bretzger/USA Today Network
Snow falls around the White House in Washington, DC, on Friday.
Snow falls around the White House in Washington, DC, on Friday.
Mandel Ngan/AFP/Getty Images
Snow falls in Charlotte, North Carolina, overnight on Friday.
Snow falls in Charlotte, North Carolina, overnight on Friday.
Peter Zay/Anadolu Agency/Getty Images
People walk through the snow on Friday, January 28, in New York City.
People walk through the snow on Friday, January 28, in New York City.
Alexi Rosenfeld/Getty Images
A bulldozer sits in front of a mountain of salt that will be used to treat roads and highways in Chelsea, Massachusetts, on Friday.
A bulldozer sits in front of a mountain of salt that will be used to treat roads and highways in Chelsea, Massachusetts, on Friday.
Joseph Prezioso/AFP/Getty Images
Slow traffic travels in the snow on Friday, in Louisville, Kentucky.
Slow traffic travels in the snow on Friday, in Louisville, Kentucky.
Matt Stone/Courier Journal/USA Today Network
A sand brim wall is put up to protect beach homes from storm waves in Winthrop, Massachusetts on Friday, January 28.
A sand brim wall is put up to protect beach homes from storm waves in Winthrop, Massachusetts on Friday, January 28.
Joseph Prezioso/AFP/Getty Images