On Dec. 18, 2015, President Obama signed a massive tax and spending bill that included a provision repealing the 40-year-old ban on U.S. crude oil exports. While the appropriations package made headlines for averting a government shutdown, it was a historic piece of legislation for U.S. energy firms.

The United States officially banned oil exports with the passage of the Energy Policy and Conservation Act of 1975 (EPCA)--a response to the 1973 OPEC oil embargo that sent gasoline prices skyrocketing, incited panic among American consumers, and highlighted the nation’s intensifying lust for energy and its precarious dependence on imported oil.

Signed into law by President Ford, EPCA also created the Strategic Petroleum Reserve--the world’s largest supply of emergency crude oil--as well as corporate average fuel economy (CAFE) standards for cars and trucks. While these and other EPCA provisions still are in place today, the domestic energy landscape has changed dramatically since the oil crisis of the 1970s.

Due to advances in hydraulic fracturing and directional drilling--often touted as the “shale revolution”--U.S. oil production is booming. According to the U.S. Energy Information Administration (EIA), the United States is the world’s largest producer of petroleum and natural gas hydrocarbons--which it attributes to the shale boom--and produced more than twice the petroleum and natural gas hydrocarbons than Saudi Arabia in 2015.

With this newfound capacity, U.S. energy firms wasted little time taking advantage of the repeal of the export ban. On Dec. 31, 2015, ConocoPhillips and NuStar Energy said they loaded the nation’s first export of U.S.-produced light crude oil since the ban was lifted on Dec. 18. A tanker carrying light sweet crude--which came via pipeline from the Eagle Ford Shale--departed from a NuStar-owned terminal in the Port of Corpus Christi (Texas) just before 4:30 p.m. that day, according to an article in the San Antonio Business Journal. Vitol, a Netherlands-based trading company, purchased the shipment.

NuStar says it has invested heavily in its operations in the Port of Corpus Christi, including spending $93 million to acquire a second terminal in 2016. The investments in additional storage space, automation technology and other assets have given the San Antonio-based pipeline and terminal operator “the ability to load export-size cargoes from its docks,” according to the company.

U.S. refiners have been upgrading and expanding their infrastructure as well, explains Alan Free, senior vice president at Chicago-based Argo Consulting.

“Most U.S. refineries were designed to process the heavier grades associated with imported oil, and we have seen new investments on the downstream end to expand flexibility to run multiple feedstocks,” Free says. “Those able to efficiently process lighter grades can now capture a competitive advantage from domestic upstream production.”

In the first five months of 2016, U.S. companies exported crude oil to 16 countries other than Canada (which has been exempted from the oil-export ban since 1985), averaging 501,000 barrels per day--9% higher than the full-year 2015 daily average. To put those numbers in perspective, U.S. exports rarely exceeded 100,000 barrels per day from 2000 to 2013, according to the EIA.