Simple answer: Money.
Oil and natural gas operations are not cheap.
A single horizontal well can cost $10 million. Power lines, water disposal systems, lease purchases and other costs add millions more.
Oklahoma City's four large, publicly traded energy companies all have billion-dollar annual drilling budgets.
Devon Energy Corp. last year completed its $750 million headquarters buildings.
There's just not that much money in Oklahoma. Or in most states, for that matter.
When SandRidge in 2007 announced plans for its initial public offering, the company said it was making the move in part to raise money to accelerate drilling and to pay for other capital expenditures.
Oklahoma-based initial public offerings raised almost $3 billion from 2005 through 2007 alone, including deals for SandRidge and Continental Resources Inc.
That's money flowing from throughout the country into Oklahoma, funding jobs, construction projects, tax revenue and all other parts of the state economy.