Located in Northeast Oklahoma, Green Country is a heavily-wooded area of the state with a relatively high amount of rolling hills, mountains and foliage as opposed to Central and Western Oklahoma, which have geography similar to "the Great Plains" region of the United States. Average rainfall totals in Green Country are generally above 40 inches per year, making it considerably wetter and greener than most of the state. The area is one of the most populated regions of Oklahoma, and contains Tulsa, the state's second-largest city.

Its name was devised in the 1960s by the Oklahoma Department of Tourism and Recreation as one of six travel destination regions within the state, but is the most historically significant of all of them, as the name's usage can be traced to the early part of the 20th century.