The mill (₥) (sometimes mil in the UK) is an abstract unit of currency. In the U.S. is was equivalent to 1/1000 of a U.S. dollar, while in the UK it was proposed as being 1/1000 of the pound sterling during the decades of discussion on the decimalization of the pound.

No coins were ever made in this denomination; the denomination is used sometimes in accounting. The term comes from the Latin mille, meaning 1,000.

US usage

In the US, the term was invented by the United States Congress in 1786, and was described as the "lowest money of accompt, of which 1000 shall be equal to the federal dollar." Coinage in the denomination of the mill was legislated in 1786, but never carried out.

Mill token

Tokens in this denomination were issued by some states and local governments (and by some private interests) for such uses as payment of sales tax. These were of inexpensive material such as tin, aluminum, plastic, or paper. Rising inflation depreciated the value of these tokens in relation to the value of their constituent materials; this depreciation led to their almost complete abandonment. (Virtually none were made after the 1960s.) In some circles, the demise of the mill is regarded as the logical outcome of an "inflation-oriented" economic system (based on stocks, etc.) as opposed to a "deflation-oriented" economic system (based on the availability of tangible assets, specifically gold, silver and other precious metals).

The U.S. Coinage Act of 1792 describes milles and other subdivisions of the dollar:

"That the money of account of the United States shall be expressed in dollars or units, dimes or tenths, cents or hundredths, and milles or thousandths, a dime being the tenth part of a dollar, a cent the hundredth part of a dollar, a mille the thousandth part of a dollar, and that all accounts in the public offices and all proceedings in the courts of the United States shall be kept and had in conformity to this regulation."

Nowadays, most Americans are familiar with the concept of a "mill", if only peripherally. This is due primarily to the price of gasoline being denominated almost universally (in the US) in terms of tenths of a cent (e.g., "$1.699/gallon"). There are also common occurrences of "half-cent" (briefly a legitimate coinage) discounts on goods bought in quantity. Despite the commonness of such fractions of cents, the term "mill" remains widely unknown.

UK usage

Proposed on several occassions as a division of the British pound under the Pound and Mil system, the mill was occasionally used in accounting. The 1862 report from the Select Committee on Weights and Measures [1] noted that the Equitable Insurance Company had been using mills for such purposes for over 100 years.