The Hazardous Materials Transportation Act (HMTA), enacted in 1975, is the principal federal law in the United States regulating the transportation of hazardous materials. Its purpose is to "protect against the risks to life, property, and the environment that are inherent in the transportation of hazardous material in intrastate, interstate, and foreign commerce" under the authority of the United States Secretary of Transportation.

The 93rd United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, D.C., from January 3, 1973, to January 3, 1975, during the last 18 months of Richard Nixon's presidency, and the first 6 months of Gerald Ford's. This Congress was the first Congress with more than two Senate presidents. After the resignation of Spiro Agnew, Gerald Ford was appointed under the authority of the newly ratified 25th Amendment. Ford became president the next year and Nelson Rockefeller was appointed in his place. The apportionment of seats in the House of Representatives was based on the 1970 United States census. Both chambers had a Democratic majority.