Outrun Change has a great post with a look at the historical number of active rigs in North Dakota. What always amazes me is that with more than 200 active rigs during the height of the boom, getting to one million bopd was "a big deal." With only 50 active rigs in North Dakota, the state is still producing a million bopd and has a thousand inactive wells (completed, but not producing) and another 900 DUCs (wells drilled to depth, but not completed/fracked).
A huge "thank you" to Outrun Change for linking the MillionDollarWay; very much appreciated. Again, the disclaimer: I often make mistakes and my data may differ from that of the NDIC for various reasons. To the best of my knowledge my data is accurate or very near accurate when it comes to rig counts as posted by the NDIC.
Some years from now, whoever writes the history of the Bakken should have no end of data from which to work.