From Old Northern French 'galon,' probably from a Gaulish Celtic root meaning 'vessel' — US and Imperial gallons diverged in 1824.
A unit of liquid capacity equal to four quarts — 3.785 liters (US) or 4.546 liters (Imperial/UK).
From Old Northern French 'galon' (a measure of liquid), probably from Vulgar Latin '*gallōnem,' possibly derived from a Gaulish (Celtic) root related to Old Irish 'gellan' (vessel) or Welsh 'galwyn' (gallon). The ultimate Celtic origin is plausible but not proven. The word appeared in English after the Norman Conquest and was standardized at different volumes over time — the US gallon (231 cubic inches
An American gallon and a British gallon are not the same size. When Britain created the Imperial gallon in 1824 (defined as the volume of 10 pounds of water), it was about 20% larger than the older English wine gallon that American colonists had already brought to the New World. So America kept the smaller gallon, and 'miles per