Outside the White House, they sang, “Nah nah nah nah, hey hey hey, good bye.” Meanwhile, neighborhoods throughout New York City suddenly erupted into dance parties.

Joe Biden supporters took to the streets Saturday to celebrate immediately after news organizations called Pennsylvania for the former vice president, giving him the 270 electoral votes he needed to win the presidency and unseat Donald Trump. 

The celebration outside the White House took place near a security fence that was erected to protect against post-election violence but, as the vote counts began to favor Biden during the week, it was covered with messages taunting the president such as “Loser” and “Eviction Notice.”

Hundreds quickly poured into Washington's Black Lives Matter Plaza to join the party.

In Times Square, Biden supporters sang and danced to NSYCN’s “Bye Bye Bye.”

 In other parts of New York City, people honked their car horns, screamed and danced.

Biden supporters also cheered in front of Trump Tower in Manhattan. 

Outside the Pennsylvania Convention Center in Philadelphia, where election workers counted votes for days, there was also dancing, and a band played in the street. 

But nearby stood pro-Trump protesters. “They’re stealing it!” one of them said. Trump has alleged, without evidence, that there was widespread election fraud and has turned to the courts to have votes disregarded. He declared victory early Wednesday morning despite that many votes in key states had yet to be counted.

In Wisconsin, a battleground state that Biden flipped to blue, a parade of cars drove by the state capitol in Madison with horns blaring. 

The scene was more subdued in Albany, New York, where protesters on both sides peacefully assembled. Biden's backers held signs reading "TRUMP MUST GO" and "DON'T MESS WITH OUR VOTE," while Trump supporters held signs that said "LEGAL VOTES ONLY" and "CAN'T STEAL OUR ELECTION."

Cheers also could be heard emanating from apartment buildings in many other cities, including Atlanta, Chicago and Seattle.

Trump supporters also gathered in droves Saturday in cities including Washington; Indianapolis; Columbus, Ohio; and Austin, Texas, where they chanted "Stop the steal."