Figures released by North Dakota’s Department of Mineral Resources showed that the state’s oil production had, for the first time, eclipsed 1 million barrels per day.

Figures released in previous months showed that North Dakota had been inching closer and closer to the 1 million mark for quite some time, however, with the cold, harsh weather experienced throughout most of the Midwest, oil output was hindered.

With oil production in the state continuing to climb, it has now entered into a unique group of regions across the globe. As of this spring, only Texas, Alberta and a handful of countries were producing more oil than the entire state of North Dakota.

The key driver behind this production surge has been the rich 25,000 square mile Bakken shale formation, which covers most of the western portion of the state, extending into Canada and parts of Montana as well.

In April of this year, total oil output from Bakken surpassed one billion barrels. North Dakota oilfields now account for approximately 12% of all domestic production and more than 1% of global production.

Overall, the Bakken boom has transformed the economic landscape of North Dakota entirely. The state now lays claim to some of the nation’s fastest growing cities along with its lowest unemployment rate, which currently stands at 2.6% (almost 4 points lower than the national average at 6.3%).

While predictions of how much recoverable oil is actually in the Bakken formation have varied significantly, some experts estimate that it could be as high as 20 billion barrels.

The U.S. Geological Survey has gone as far to call Bakken the largest continuous oil accumulation it has ever assessed.