The US lifted its 40-year ban on oil exports on 18 December as part of a $1.1 trillion spending bill that was approved by Congress and is now due to be signed by President Barack Obama.

The ban was introduced in 1975, along with the Strategic Petroleum Reserve, in the wake of the 1973-74 Arab oil embargo, which pushed up oil prices and dealt a blow to the US economy.

America’s Strategic Petroleum Reserve is an emergency stockpile of oil maintained by the US Department of Energy. It has the capacity to hold up to 713.5 million barrels, making it the largest emergency supply in the world.

The end of the ban means that the 9.2 million barrels a day produced in the US and the 490.7 million barrels stockpiled commercially are now available for export.

US President Barack Obama still retains the ability to limit exports in the case of a national emergency, or if exports cause domestic oil shortages.

Over recent years, US oil production has boomed due to the rise of new technology that has made it cost-effective to exploit unconventional resources.

The US could become a net exporter of crude oil in the next decade, according to the US Department of Energy.

Lifting the ban is not expected to have a significant impact on global oil prices.