<P> The majority of U.S. customary units were redefined in terms of the meter and the kilogram with the Mendenhall Order of 1893 and , in practice , for many years before . These definitions were refined by the international yard and pound agreement of 1959 . Americans primarily use customary units in commercial activities , as well as for personal and social use . In science , medicine , many sectors of industry and some of government and military , metric units are used . The International System of Units ( SI ) , the modern form of the metric system , is preferred for many uses by the U.S. National Institute of Standards and Technology ( NIST ) . For newer units of measure where there is no traditional customary unit , international units are used , sometimes mixed with customary units , such as electrical resistance of wire expressed in ohms ( SI ) per thousand feet . </P>
what kind of metric system does the us use
The International System of Units ( SI ) international units