The U.S. has nosed ahead of Saudi Arabia and is on pace to surpass Russia to become the world’s biggest oil producer for the first time in more than four decades.

The latest forecast from the U.S. Energy Information Administration predicts that U.S. output will grow next year to 11.8 million barrels a day.

“If the forecast holds, that would make the U.S. the world’s leading producer of crude,” says Linda Capuano, who heads the agency, a part of the Energy Department.

Saudi Arabia and Russia could upend that forecast by boosting their own production. In the face of rising global oil prices, members of the OPEC cartel and a few non-members including Russia agreed last month to ease production caps that had contributed to the run-up in prices.

The idea that the U.S. could ever again become the world’s top oil producer once seemed preposterous.

“A decade ago the only question was how fast would U.S. production go down,” said Daniel Yergin, author of several books about the oil industry. The rebound of U.S. output “has made a huge difference. If this had not happened, we would have had a severe shortage of world oil,” he said.

The United States led the world in oil production for much of the 20th century, but the Soviet Union surpassed America in 1974, and Saudi Arabia did the same in 1976, according to Energy Department figures.

By the end of the 1970s the USSR was producing one-third more oil than the U.S.; by the end of the 1980s, Soviet output was nearly double that of the U.S.

The last decade or so has seen a revolution in American energy production, however, led by techniques including hydraulic fracturing, or fracking, and horizontal drilling.

Those innovations—and the breakup of the Soviet Union—helped the U.S. narrow the gap. Last year, Russia produced more than 10.3 million barrels a day, Saudi Arabia pumped just under 10 million, and the U.S. came in under 9.4 million barrels a day, according to U.S. government figures.