NJ Transit says all the trains had power and heat and the customers were okay.
Amtrak spokesman Cliff Cole says power was restored around 11:30 a.m. Wednesday after a three-hour stoppage.
Cole says delays have decreased for trains operating between Boston and Washington. Amtrak trains were running on schedule or close to it by 4:00 p.m., he said. But, when Nina Pineda checked the Penn Station boards at 6:00 p.m., the trains were still running up to an hour behind schedule.
Customers are urged to go to www.njtransit.com for the latest service information. Service information is also available by calling 973-275-5555.
For Amtrak information, go to, www.amtrak.com
A low-voltage reading originating in North Bergen, N.J., where trains go under the Hudson River en route to Manhattan, caused the problems.
Amtrak was investigating what caused the low voltage reading. Cole said trains can continue running at low voltage but are routinely moved to the nearest station to avoid the possibility of a larger power failure.
The stoppage stranded thousands of travelers on trains and in stations from Boston to Washington, D.C. Some commuters in New York and New Jersey were able to switch to subway trains in and out of the city, but others weren't as fortunate.
At Penn Station in New York City, travelers packed a waiting area, sitting on suitcases with bags of holiday gifts scattered around them on the floor. A display board showed grim news for every train.
Lyn Hunt and four family members had been traveling since Saturday - or trying to. Their trip to Newark from England had to be rerouted through Chicago because of the snowstorm that swept up the East Coast over the weekend.
The family then traveled by Amtrak from Chicago to New York, only to be delayed again Wednesday as they tried to take a train north.
"We've decided that our motto is adapt, improvise and overcome," Hunt said. "We don't know yet how we will adapt or overcome this."
Her answer came just before noon when an announcement crackled over the loudspeaker that power had been restored and trains would begin rolling again.
At Washington's Union Station, at least one train was announced as canceled and some passengers said they were told by Amtrak personnel that the problems were related to cold weather.
At Philadelphia's 30th Street Station, trains were delayed one to almost three hours, and frustrated holiday travelers gathered throughout the station.
Nicole West-Burns, who was getting off a southbound train, said Amtrak told her and other passengers getting on in Philadelphia on Wednesday morning that the doors were frozen shut.
In Trenton, a train bound for Vermont broke down and passengers were forced to move to an arriving Amtrak Keystone service train. They were taken to New York City, where they would need to change trains again if they planned to continue north.
The delays came days after Amtrak sent out a news release touting its efficiency in moving travelers during last weekend's major snowstorm in the same region.
"Over the weekend Amtrak carried thousands of people to their destinations when others couldn't - and we did so safely," the release reads. "We accommodated numerous travelers who gave up on the airlines. ... Amtrak stepped up, met the challenge, and once again proved to be a vital transportation link."
(Information from the Associated Press was used in this article)