Airlines resumed flights from the United States to Mexico City on Friday after halting them on Thursday as a precaution because of volcanic activity on Popocatepetl.
Routes affected by the cancellations were flights to Houston, Dallas, Denver, Phoenix, Chicago and Los Angeles.
The BBC reports US Airways, Delta, United, American and Alaska Airlines returned to their normal schedules on Friday.
Mexican airlines continued to fly into the airport as scheduled.
American Airlines said in a statement that the cancellation was a precaution.
"We are closely monitoring the situation in Mexico City as volcanic ash continues to be emitted from Popocatepetl," said spokesman Matt Miller.
The BBC reports a no-go zone is in place for 11km around the volcano, which is 55km from Mexico City.
Ash and a fountain of hot rock have been flowing from Popocatepetl since May.
Several tremors were reported around the volcano on Thursday.