I'd imagine it has something to do with the timeframe that terms describing units of electricity came into common usage.
The U.S. is a signatory of the Metre Convention (1875). All of our customary units are defined as linear conversions of corresponding SI units. The Watt and Joule (also Ohm) were not standardized until 1893. Funnily enough, the international conference where these were officially decided happened in Chicago.
The U.S. is a signatory of the Metre Convention (1875). All of our customary units are defined as linear conversions of corresponding SI units. The Watt and Joule (also Ohm) were not standardized until 1893. Funnily enough, the international conference where these were officially decided happened in Chicago.