The oil fields of North Dakota have reached a major milestone as they are now producing more than 1 million barrels of crude oil per day.
The state's Department of Mineral Resources reported Tuesday that the 1 million-barrel mark was surpassed in April, primarily from the rich Bakken shale formation in the western part of the state.
In March, the state produced 977,000 barrels per day.
North Dakota is one of only five states to have reached that production milestone. The others are Texas, Alaska, California and Louisiana, and only Texas is still producing above that level at about 3 million barrels per day, according to Bloomberg News.
Production will increase through the summer as better weather allows crews to finish more wells, said Lynn Helms, the department’s director, during a conference call with reporters Tuesday. He expects production to grow to 1.5 million barrels a day by 2017, the Associated Press reports.
North Dakota's oil industry has grown rapidly over the past five years or so, as new technologies like hydraulic fracturing, or fracking, have made it possible to extract oil from the layers of shale rock that sit a mile or more underground. North Dakota's oil fields now represent more than 12 percent of all U.S. oil production, according to the Associated Press.
The oil boom has also transformed the economy of western North Dakota. Workers from around the country have come there in droves to find jobs. But the rapid growth has strained local resources like housing, roads, schools and police departments.
Others are concerned about the safety of the shale oil as it's transported by rail across the country. There have been several recent accidents involving oil trains which have led to oil spills, explosions and fires.
Federal officials and lawmakers are proposing stricter regulations of oil trains to improve their safety and provide for better response in case of an emergency.