The recent contraction of oil drilling because of increased efficiency, visualized by Bloomberg:
These four years of data represent the fastest expansion of oil production in U.S. history. New technology drove this boom—particularly the deployment of horizontal drilling through shale rock. The three biggest oil-producing shale regions are the Permian basin in West Texas, the Eagle Ford in Southern Texas, and the Bakken in North Dakota. Hover on the map for drilling history in each basin.As the price of oil plunged in the second half of last year, producers started shutting down rigs at an unprecedented rate. First to go were rigs that operated without long-term contracts. Then companies began terminating agreements early and letting expired contracts go unrenewed. Active rigs declined by more than 40 percent. Remaining drilling efforts have focused on the most productive oil regions—sweet spots where oil will be profitable even at $40 a barrel.