Corey Properties

With more than 2 million customers in Oklahoma, Kansas and Texas, ONEOK is among the largest natural gas distributors in the United States. This diversified energy company is a leader in the gathering, processing, storage and transportation of natural gas in the mid-continent region of the U.S., and it owns one of the nation's premier natural gas liquids systems. In addition, ONEOK's energy services operation is focused on marketing natural gas and related services throughout the U.S. Founded in 1906, this Fortune 500 company is traded on the New York Stock Exchange. It is headquartered in Tulsa, Okla.