And the weather posed challenges a week out for how to get everyone out to vote. On the hard-hit New Jersey coastline, a county elections chief said some polling places on barrier islands will be unusable and have to be moved.
"This is the biggest challenge we've ever had," said George R. Gilmore, chairman of the Ocean County Board of Elections.
By Tuesday afternoon, there were still only hints of the economic impact of the storm. Airports remained closed across the East Coast and far beyond as tens of thousands of travelers found they couldn't get where they were going.
IHS Global Insight, a forecasting firm, predicted the storm will end up causing about $20 billion in damages and $10 billion to $30 billion in lost business - big numbers probably offset by reconstruction and repairs that will contribute to longer-term growth. Americans can also expect higher gas prices in the short term.
"The biggest problem is not the first few days but the coming months," said Alan Rubin, an expert in nature disaster recovery.
Sandy began in the Atlantic and knocked around the Caribbean -- killing nearly 70 people -- and strengthened into a hurricane as it chugged across the southeastern coast of the United States. By Tuesday night it had ebbed in strength but was joining up with another, more wintry storm - an expected confluence of weather systems that earned it nicknames like "superstorm" and, on Halloween eve, "Frankenstorm."
It became, pretty much everyone agreed Tuesday, the weather event of a lifetime -- and one shared vigorously on social media by people in Sandy's path who took eye-popping photographs as the storm blew through, then shared them with the world by the blue light of their smartphones.
On Twitter , Facebook and the photo-sharing service Instagram, people tried to connect, reassure relatives and make sense of what was happening -- and, in many cases, work to authenticate reports of destruction and storm surges. They posted and passed around images and real-time updates at a dizzying rate, wishing each other well and gaping, virtually, at scenes of calamity moments after they unfolded. Among the top terms on Facebook through the night and well into Tuesday, according to the social network: "we are OK," "made it" and "fine."
Around midday Tuesday, Sandy was about 120 miles east of Pittsburgh, pushing westward with winds of 45 mph, and was expected to turn toward New York State on Tuesday night. Although weakening as it goes, the storm will continue to bring heavy rain and flooding, said Daniel Brown of the National Hurricane Center in Miami.
Atlantic City's fabled Boardwalk, the first in the nation, lost several blocks when Sandy came through, though the majority of it remained intact even as other Jersey Shore boardwalks were dismantled. What damage could be seen on the coastline Tuesday was, in some locations, staggering - "unthinkable," New Jersey Gov. Chris Christie said of what unfolded along the Jersey Shore, where houses were swept from their foundations and amusement park rides were washed into the ocean. "Beyond anything I thought I would ever see."
Resident Carol Mason returned to her bayfront home to carpets that squished as she stepped on them. She made her final mortgage payment just last week. Facing a mandatory evacuation order, she had tried to ride out the storm at first but then saw the waters rising outside her bathroom window and quickly reconsidered.
"I looked at the bay and saw the fury in it," she said. "I knew it was time to go."
Contributing to this report were Katie Zezima in Atlantic City, N.J.; Alicia Caldwell and Martin Crutsinger in Washington; Colleen Long, Jennifer Peltz, Tom Hays, Larry Neumeister, Ralph Russo and Scott Mayerowitz in New York; Meghan Barr in Mastic Beach, N.Y.; Christopher S. Rugaber in Arlington, Va.; Marc Levy in Harrisburg, Pa.: John Christoffersen in Bridgeport, Conn.; Vicki Smith in Elkins, W.Va.; David Porter in Newark, N.J.; Joe Mandak in Pittsburgh; and Dave Collins in Hartford, Conn.
Follow Ted Anthony on Twitter at http://twitter.com/anthonyted