The largest of our core areas, the Northern Delaware Basin, has rapidly advanced from an exploration play to large-scale development. Over the past three years, most of our companywide activity has focused on the Northern Delaware Basin, and some of our best projects are here. The Northern Delaware Basin has delivered record production across a large geographic area spanning three counties and nine distinct zones. Results from our drilling program, completion optimization efforts, and down-spacing increased our inventory in the Northern Delaware Basin during 2016.
During 2016, we announced an opportunistic bolt-on transaction that increased our footprint in Southern Lea County by more than 25%. We continue to capture, define and de-risk our resource, and believe there is upside potential from reducing both the spacing between wells and optimizing our completion design in the Northern Delaware Basin.