A barrel is also used to measure liquids. One barrel of oil is 158.987 litres (42 US gallons). It is shortened as "bbl". This use may have come from the early Pennsylvanian oil fields where wooden barrels were used to store and move oil around. In 1866, the people of West Virginia started using it regularly. At this time, the amount was set to 42 American gallons. It was later world-wide for measuring amounts of oil and pricing it. Today, oil is rarely stored or transported in actual barrels, but the term "barrel" is still used to mean a 42-gallon measurement.