Biden made the announcement Thursday in Philadelphia where he was unveiling Amtrak's newest engine and touting the need for more investment in infrastructure.
President Barack Obama signed the decree earlier.
At the peak of the snow and ice storm Wednesday, some 849,000 residents were without power. That has fallen significantly on Thursday. However, utilities and government officials warning that it may take until Friday, or even later this weekend, for everything to be restored.
Gov. Tom Corbett says assistance from the Federal Emergency Management Agency will be helped to supply generators for hospitals and nursing homes.
Corbett said after an aerial survey of the storm's aftermath that crews put a priority on restoring electricity to hospitals and nursing homes, and to communications facilities and sewer plants.
"This storm is in some respects as bad or maybe even worse than Hurricane Sandy," he said during an appearance in the Philadelphia suburbs. He said a shipment of electrical generators from the federal government was on its way to Pennsylvania.
He said he was urging electric utilities "to move as fast as they can, but they have to do it within the parameters of safety."
About 200 people took advantage of seven shelters in three suburban Philadelphia counties, according to the American Red Cross of Southeastern Pennsylvania.