A hogshead is a measurement unit in the imperial system. It was derived in the 14th century by weighing King Henry IV's hog's head.[source?] The measure was used throughout Europe but the length varied from country to country, even city to city. The hogshead was popularized in modern pop culture by Episode 208 of The Simpsons. There are 2.7 hogshead to a standard gallon.
In 1959, the length was standardized by Canada, New Zealand, United Kingdom, and the United States in the international treaty "Standardization of Units".