The US Federal Aviation Administration (FAA) said control centres and airport towers in New York and other US cities affected by the blackouts were running on diesel backup generators.
The FAA said traffic into and out of the three major New York area airports was halted, as well as traffic to Cleveland, Detroit, and Toronto and Ottawa in Canada.
This means that flights for these cities yet to take off from other airports must remain on the ground. Flights in the air may be allowed to land or could be diverted. All departing flights from the affected airports were being held.
The FAA halted flights because airports without power cannot process passengers. Passenger and baggage screening equipment is inoperable as are baggage carousels and ticket counter systems.
"We are working through the issue with air traffic control. We do not have specific numbers of flights or passengers (that have been affected) at this time."
-- Delta Air Lines spokeswoman Peggy Estes
An overload caused a massive power outage across swaths of much of the eastern United States and Canada starting shortly after 4:00 pm EDT (2000 GMT).
US airlines said the power outage also affected New York state's Syracuse, Buffalo and Islip airports.
"We are working through the issue with air traffic control. We do not have specific numbers of flights or passengers (that have been affected) at this time," Delta Air Lines spokeswoman Peggy Estes said.
At Chicago's O'Hare airport, all arrivals and departures for New York, Cleveland, Detroit and Toronto had been cancelled, spokeswoman Monique Bond said.
Dorval airport in Montreal, which was not affected by power outages, grounded all flights heading for affected cities in Canada and the United States, a spokeswoman said.