The Williston Basin formation has emerged in recent years as one of the most important sources of new oil production in the United States. Most Williston Basin drilling and production has been in North Dakota, although the formation also extends into Montana and the Canadian provinces of Saskatchewan and Manitoba. As of 2013, the Williston Basin was the source of more than ten percent of all US oil production. By April 2014, Williston Basin production in North Dakota and Montana exceeded 1 million barrels per day (160,000 m3/d).