page_title: Imperial and US customary measurement systems
section_title: United States customary units
hierarchical_section_title: Imperial and US customary measurement systems / United States customary units
caption_attribution_description: English: Pound Troy constructed by the Office of Weights and Measures in the Coast Survey - ca. 1832-1839
context_page_description: The Imperial and US customary measurement systems are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.
  The US Customary system of units was developed and used in the United States after the American Revolution, based on a subset of the English units used in the Thirteen Colonies. The Imperial system of units was developed and used in the United Kingdom and its empire beginning in 1826. US Customary units are the predominant system of units in the United States and the metric system has, to varying degrees, replaced the imperial system in the countries that used it.
  Most of the units of measure have been adapted in one way or another since the Norman Conquest. The units of linear measure have changed the least – the yard and the chain were measures derived in England. The foot used by craftsman supplanted the longer foot used in agriculture. The agricultural foot was reduced to ​¹⁰⁄₁₁ of its former size, causing the rod, pole or perch to become ​16 ¹⁄₂ agricultural feet.
context_section_description: Prior to their declaration of independence in 1776, the thirteen colonies that were to become the United States used the English system of measurement. The Articles of Confederation which predated the Constitution gave the central government "the sole and exclusive right and power of...fixing the Standard of Weights and Measures throughout the United States." Subsequent to the formation of the United States, the Constitution reaffirmed the right of Congress to "fix the Standard of Weights and Measures" but reserved the right to regulate commerce and weights and measures to the individual states.
  During the First Congress of the United States in 1789, Thomas Jefferson was detailed to draw up a plan for the currency and weights of measures that would be used in the new republic. In his response in 1790 he noted that the existing system of measure was sound but that control of the base artefact was not under the control of the United States. His report suggested a means of manufacturing a local standard and also left the way open for an adoption of a decimal-based system should this be appropriate. In the event, the existing standards were retained.
  For many years no action was taken at the federal level to ensure harmony in units of measure – the units acquired by the early colonists appeared to serve their purpose. Congress did nothing, but Ferdinand Hassler, Superintendent of the East Coast survey, who in 1790 had met using contacts in his native Switzerland acquired a copy of the [French] mètre des Archives. 
  In 1810 Ferdinand Hassler was dispatched to Europe by the Treasury to acquire measuring instruments and standards.
  In 1827 Albert Gallatin, United States minister at London acquired an "exact copy" of the troy pound held by the British Government which in 1828 was adopted as the reference copy of weight in the United States.
  In 1821 John Quincy Adams, then Secretary of State submitted a report based on research commissioned by the Senate in 1817 which recommended against adoption of the metric  system. Congress did nothing and in 1832 the Treasury adopted the yard of 36 inches as the unit of length for customs purposes, the avoirdupois pound of 7000 grains as the unit of weight and the gallon of 231 cubic inches (the "Queen Anne gallon") and the bushel of 2150.42 cubic inches as the units of volume. Congress did little to promote standards across the United States other than fixing the size of the yard and the gallon. 
  Throughout the nineteenth century individual states developed their own standards and in particular a variety of bushels based on weight (mass) rather than volume emerged, dependent on both commodity and state.  This lack of uniformity crippled inter-state trade and in 1905 the National Bureau of Standards called a meeting of the states to discuss the lack of uniform standards and in many cases, a means of regulatory oversight. A meeting was held the following year and subsequently became an annual gathering known as the National Conference on Weights and Measures (NCWM).  In 1915 the conference published its first model standards.  The bushel was not fully standardized and the Chicago Mercantile Exchange still (May 2013) uses different bushels for different commodities—a bushel of corn being 56 lb, a bushel of oats 38 lb and a bushel of soybeans 60 lb and a bushel of red winter wheat (both hard and soft) also 60 lb.  Other commodities at the exchange are reckoned in pounds, in short tons or in metric tons.
  One of the actions taken by Congress was to permit the use of the metric system in trade (1866), made at the height of the metrication process in Latin America. Other actions were to ratify the Metre Convention in 1875 and under the Mendenhall Order of 1897, to redefine the pound and the yard in terms of the international prototype of the kilogram and the international prototype of the metre respectively.
  In 1901 the administration of weights and measures was handed to a federal agency, the National Bureau of Standards, which in 1988 became the National Institute of Standards and Technology.  Inac
caption: Pound Troy constructed by the Office of Weights and Measures in the Coast Survey – c. 1832–39
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