The Metric Conversion Act of 1975 is an Act of Congress that was signed into law by U.S. President Gerald Ford on December 23, 1975.^[1] It declared the metric system "the preferred system of weights and measures for United States trade and commerce", but permitted the use of United States customary units in all activities. As Ford's statement on the signing of the act emphasizes, all conversion was to be "completely voluntary".^[1] The Act also established the United States Metric Board with representatives from scientific, technical, and educational institutions, as well as state and local governments to plan, coordinate, and educate the U.S. people for the Metrication of the United States.

The Metric Board was abolished in 1982 by President Ronald Reagan, largely on the suggestion of Frank Mankiewicz and Lyn Nofziger.^[2]

Executive Order 12770, signed by President George H. W. Bush on July 25, 1991, directed departments and agencies within the executive branch of the United States Government to "take all appropriate measures within their authority" to use the metric system "as the preferred system of weights and measures for United States trade and commerce" and authorized the Secretary of Commerce "to charter an Interagency Council on Metric Policy ('ICMP'), which will assist the Secretary in coordinating Federal Government-wide implementation of this order."

• History of the metric system
• Omnibus Foreign Trade and Competitiveness Act of 1988
• US Metric Association