The Federal Aviation Administration said on Wednesday that 43 flights into New Jersey's Newark Liberty International Airport were required to hold after drone sightings at a nearby airport on Tuesday, while nine flights were diverted.
The incident comes as major U.S. airports are assessing the threat of drones and have been holding meetings to address the issue.
The issue of drones impacting commercial air traffic came to the fore after London's second-busiest airport, Gatwick Airport, was severely disrupted in December when drones were sighted on three consecutive days.