The world's busiest airport and 39 others across the United States were forced to decrease flights by 10 percent starting on Nov. 7.

The Federal Aviation Administration (FAA) announced the decision on Nov. 4, as it struggles with personnel shortages due to the ongoing government shutdown. Those flight controllers who stay on continue to work without pay.

"We can't ignore it," FAA Administrator Bryan Bedford said at a press conference on Nov. 4.

"If the pressures continue to build even after we take these measures, we'll come back and take additional measures."

Beford added that he was unaware of the FAA taking any measures like this in his 35 years in the aviation industry.

The airports affected are:

Ted Stevens Anchorage International in Alaska.

Hartsfield-Jackson Atlanta International in Georgia

Boston Logan International in Massachusetts

Baltimore/Washington International in Maryland

Charlotte Douglas International in North Carolina

Cincinnati/Northern Kentucky International in Ohio

Dallas Love Field in Texas

Ronald Reagan Washington National in Virginia

Denver International in Colorado

Dallas/Fort Worth International in Texas

Detroit Metropolitan Wayne County in Michigan

Newark Liberty International in New Jersey

Fort Lauderdale/Hollywood International in Florida

Honolulu International in Hawaii

Houston Hobby in Texas

Washington Dulles International in Virginia

George Bush Houston Intercontinental in Texas

Indianapolis International in Indiana

John F. Kennedy International in New York

Harry Reid International Airport in Las Vegas

Los Angeles International in California

LaGuardia Airport in New York

Orlando International in Florida

Chicago Midway International in Illinois

Memphis International in Tennessee

Miami International in Florida

Minneapolis/St Paul International in Minnesota

Oakland International in California

Ontario International in California

Chicago O`Hare International in Illinois

Portland International in Oregon

Philadelphia International in Pennsylvania

Phoenix Sky Harbor International in Arizona

San Diego International in California

Louisville International in Kentucky

Seattle/Tacoma International in Washington

San Francisco International in California

Salt Lake City International in Utah

Teterboro in New Jersey

Tampa International in Florida