Fly America Act

The Fly America Act of 1974 is a federal law (Title 49 U.S. Code, Section 40118) established a legal requirement that all government-financed air travel be performed by U.S. air carrier services where such service is available. All flights (domestic and international) supported with federal funds must be taken on U.S. flag air carriers, regardless of cost or convenience—unless an exception, as listed in the Federal Travel Regulation (FTR), is authorized.   

Important Note: Under the Fly America Act, domestic travel includes travel within and between the United States, its territories and possessions. Travel outside these specified areas is considered international travel, including travel to Canada and Mexico. There are some federal agencies that treat travel to Canada and Mexico as domestic travel for award budgetary purposes, but this treatment doesn't exempt travel to these countries from the Fly America Act.