Kuskokwim wrote:

1959
UK and USA redefine the inch to be 2.54 cm. In 1963 the UK redefines the
pound to be exactly 0.45359237 kilograms. In 1985 the UK redefines the
gallon to be exactly 3.785411764 liters. The USA took similar steps,
although the USA gallon is smaller and consequently has been redefined as
3.785411784 liters.

Isn't the Imperial Gallon 4.54609 liters?