GALLON (U.S.)

A unit of capacity, containing four quarts, used in the United States primarily for liquid measure. One U.S. gallon contains 231 cubic inches, 0.133 cubic feet, or 3.7853 liters. One U.S. gallon is equivalent to the volume of 8.3359 pounds av. (avoirdupois) of distilled water at its maximum density (32.9°F or 4°C), weighed in dry air at the same temperature against brass weight of 8.4 density and with the barometer at 30 inches. It takes approximately 325,851 gallons to make up 1 acre-foot (AF). (Historical Note: The U.S. gallon is the same as the old English wine gallon which was originally intended in England to be equivalent to a cylinder of seven inches in diameter and six inches in height.)