The shale oil boom that turned the U.S. into the world’s largest fuel exporter and brought $3 gasoline back to America’s pumps is grinding to a halt.

With the Organization of Petroleum Exporting Countries (OPEC) maintaining its own oil production, U.S. shale is coming under pressure to rebalance a global supply glut. EOG Resources Inc., the country’s biggest shale-oil producer, hedge fund manager Andrew J. Hall and banks including Standard Chartered Plc have forecast declines in U.S. output following last year’s plunge in crude prices. The nation was still pumping the most in four decades in March.

“Production has to come down because rigs drilling for oil are down 57 percent this year,” James Williams, president of energy consultancy WTRG Economics, said by phone Monday from London, Arkansas. “Countering that is the fact that the rigs we’re still using are more efficient and drilling in areas where you get higher production. So that has delayed the decline.”