CNN Money: The resurgence of the oil industry can be traced back to what happened in Congress one day in December 2015.

That’s when lawmakers ended the 40-year ban on U.S. oil exports. Crude pumped in Texas, Oklahoma and North Dakota could suddenly be shipped overseas.

At the time, a glut of supply was wreaking havoc on the energy industry. Crude eventually crashed to $26 a barrel.

But that glut is disappearing, thanks in part to booming oil exports from the United States. Crude that was once trapped inside the country is now going to Europe, Latin America and even China.

The United States exported a record 1.7 million barrels of oil per day in October 2017, according to the most recent stats from the Energy Information Administration. That’s four times as much as in 2015, when federal law prohibited shipping oil to most places except Canada.  Read more.