Travelers were showing up at the airport without reservations, The Washington Post reported.
Witnesses at two terminals told the Post the situation was chaotic, with areas packed with people and luggage, making it impossible to reach ticket counters.
The government blocked Internet access for a fourth day to prevent demonstrators involved in a massive protest against the government from communicating with each other.
Cellphone service was spotty and landline telephone service failed frequently in recent days, travelers said.
Delta Airlines canceled flights from Egypt to New York, prompting U.S. citizens in Egypt to seek travel to European or Middle Eastern destinations if possible.
Lufthansa, Air France, Kuwait Airways and Egypt Air all reported flight cancellations or disruptions, the Post said.
The United States and several other countries sent planes to evacuate their citizens.