oklahoma's 10 geographic regions are defined by surface features called
ecological regions
title: Geography of Oklahoma text: and with 200 lakes created by dams, it holds the highest number of reservoirs in the nation. Oklahoma covers an area of , with of land and of water, making it the 20th-largest state in the United States. Generally, it is divided into seven geographical regions: Green Country, or Northeast Oklahoma, Southeastern Oklahoma, Central Oklahoma, South Central Oklahoma, Southwest Oklahoma, Northwest Oklahoma, and the Oklahoma Panhandle. Situated between the Great Plains and the Ozark Plateau in the Gulf of Mexico watershed, Oklahoma tends to slope gradually downward from its western to eastern boundaries. Its highest and lowest points follow this title: Oklahoma text: Oklahoma Oklahoma () is a state in the South Central region of the United States, bordered by Kansas on the north, Missouri on the northeast, Arkansas on the east, Texas on the south, New Mexico on the west, and Colorado on the northwest. It is the 20th-most extensive and the 28th-most populous of the fifty United States. The state's name is derived from the Choctaw words and , meaning "red people". It is also known informally by its nickname, "The Sooner State", in reference to the non-Native settlers who staked their claims on land before the official opening date of title: Geography of Oklahoma text: Geography of Oklahoma The Geography of Oklahoma encompasses terrain and ecosystems ranging from arid plains to subtropical forests and mountains. Oklahoma contains 10 distinct ecological regions, more per square mile than in any other state by a wide margin. It is situated in the Great Plains and U.S. Interior Highlands region near the geographical center of the 48 contiguous states. Usually considered part of the South Central United States, Oklahoma is bounded on the east by Arkansas and Missouri, on the north by Kansas, on the northwest by Colorado, on the far west by New Mexico, and on the south title: Oklahoma text: anchors, with nearly two thirds of Oklahomans living within their metropolitan statistical areas. With ancient mountain ranges, prairie, mesas, and eastern forests, most of Oklahoma lies in the Great Plains, Cross Timbers, and the U.S. Interior Highlands, a region prone mainly to severe weather. More than 25 Native American languages are spoken in Oklahoma, ranking third behind Alaska and California. Oklahoma is on a confluence of three major American cultural regions and historically served as a route for cattle drives, a destination for Southern settlers, and a government-sanctioned territory for Native Americans. The name "Oklahoma" comes from the Choctaw phrase title: Oklahoma text: its highest peak, Black Mesa, at above sea level, situated near its far northwest corner in the Oklahoma Panhandle. The state's lowest point is on the Little River near its far southeastern boundary near the town of Idabel, Oklahoma, which dips to above sea level. Among the most geographically diverse states, Oklahoma is one of four to harbor more than 10 distinct ecological regions, with 11 in its borders—more per square mile than in any other state. Its western and eastern halves, however, are marked by extreme differences in geographical diversity: Eastern Oklahoma touches eight ecological regions and its western