United States customary units
United States customary units form a system of measurement units commonly used in the United States and most U.S. The system developed from English units that were in use in the British Empire before the U.S. became an independent country. While many U.S. units are essentially similar to their imperial counterparts, there are noticeable differences between the systems.
- field
- Measurement system
- nationality
- United States
- known_for
- System of measurement units used in the U.S. and its territories
- refined_by_international_agreement
- 1959
Lore & Background
Both systems derive from English units, which had evolved over millennia before American independence, with roots in Roman and Anglo-Saxon units. The customary system was championed by the U.S.-based International Institute for Preserving and Perfecting Weights and Measures in the late 19th century; some advocates saw the metric system as atheistic, with one Ohio auxiliary president writing that traditional units were 'a just weight and a just measure, which alone are acceptable to the Lord.'
Reader's Guide
The U.S. customary system remains widely used in commercial activities, personal and social use, and industrial manufacturing, while metric units are standard in science, medicine, engineering, and many sectors of industry and government, including the military. The U.S. However, implementation of metrication has been limited. The U.S. is one of three nations (along with Liberia and Myanmar) that have not adopted the metric system as their official system. The customary system's length units—inch, foot, yard, and mile—were redefined in 1959 based on the international yard and pound agreement, though the U.S.
Did You Know?
- The U.S. is one of three nations (along with Liberia and Myanmar) that have not adopted the metric system as their official system.
Frequently Asked Questions
How does United States customary units's story end?
There is no final chapter; the system is still in active, nationwide use today. Its ongoing 'arc' is one of gradual alignment with metric definitions while preserving the familiar unit names Americans grew up with.
Why is United States customary units important?
It underpins virtually every sector of American industry, from engineering to cooking, making it a practical necessity for the country. Although many of its units closely mirror British imperial ones, there are meaningful differences that keep the two systems distinct.
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