The United States may be the only industrialized country in the world that does not use the metric system as its predominant system of measurement, but we have been using it for a long time.
In 1866, Congress authorized the use of the metric system in this country and gave each state a set of standard metric weights and measures.
In 1875, the United States firmed its commitment to the development of the internationally recognized metric system by becoming one of the original seventeen signatory nations to the Treaty of the Meter. In 1893, metric standards, developed through international cooperation were adopted as the fundamental standards for length and mass in the United States.
The General Conference of Weights and Measures, the governing body that has overall responsibility for the metric system, and which is made up of the signatory nations to the Treaty of the Meter, approved an updated version of the metric system in 1960. This modern system is called Le Système International d'Unités or the International System of Units, abbreviated SI.
The United Kingdom, began a transition to the metric system in 1965 to more fully mesh its business and trade practices with those of the European Common Market. The conversion of the United Kingdom to SI created a new sense of urgency regarding the use of metric units in the United States.
A detailed U.S. Metric Study was conducted by the Department of Commerce. The final report of the study, "A Metric America: A Decision Whose Time Has Come," concluded that the U.S. would eventually join the rest of the world in the use of the metric system of measurement. The study recommended that the United States implement a carefully planned transition to predominant use of the metric system over a ten-year period.
Congress passed the Metric Conversion Act of 1975 "to coordinate and plan the increasing use of the metric system in the United States." A process of voluntary conversion was begun, and the U.S. Metric Board was established. But the efforts of the Metric Board were largely ignored by the American public, and, in 1981, the Board reported to Congress that it lacked the clear Congressional mandate necessary to bring about national conversion. In 1982 the Board was dissolved.
The Board's demise increased doubts about the United States' commitment to metrication. Public and private sector metric transition slowed at the same time that the very reasons for the United States to adopt the metric system---the increasing competitiveness of other nations and the demands of global marketplaces---made completing the conversion even more important.
Congress, recognizing the necessity of the United States' conformance with international standards for trade, included new encouragement for U.S. industrial metrication in the Omnibus Trade and Competitiveness Act of 1988. This legislation amended the Metric Conversion Act of 1975 and designated the metric system as the "preferred system of weights and measures for United States trade and commerce." The legislation states that the Federal Government has a responsibility to assist industry, especially small business, as it voluntarily converts to the metric system of measurement.
While not mandating metric use in the private sector, the Federal Government has sought to serve as a catalyst in the metric conversion of the country's trade, industry, and commerce.