US Customary system

The system for weights and other measures in general use in the USA. Founded on the measures in use in Britain before the introduction of BI in 1825, the US-C is essentially the BI system except for volumetric measures, where the old British wine gallon of 231 cubic inches became the standard for liquids and the Winchester bushel of England the standard for dry goods. The last, specified as dimensions of a round container, bore no simple relationship to the wine gallon.

The first formal action to establish a national system of ‘Weights and Measures’ in the USA did not occur until 1830, i.e. five years after the introduction of BI. The foot, etc., for length, and the pound, etc., for ‘weight’, were intended to equal the British values, though various related terms were used differently, notably the hundredweight, reset to its original 100 lb, and the ton. However, minor variation of sizing did occur, particularly through the statute of 1866 that led to the Mendenhall Order. Like BI, the US-C has three distinct (though closely interrelated) schemes for mass: avoirdupois scale (US-C-av), troy scale (US-C-troy) and apothecaries' scale (US-C-ap). See grain.