In the United States, major changes were made to the key transportation regulations in 1991. That was a direct result of the rest of the world saying no to the United States; in essence, the international community said the United States could no longer use its own definitions and its arbitrary system of measurements if they wished to export product to the rest of the world. The original United States hazardous materials transportation regulation is known as the Hazardous Materials Transportation Act of 1974 or HMT. The much more critical act is the 1990 Hazardous Materials Transportation Uniform Safety Act (HMTUSA).