Oklahoma is one of the 48 contiguous states of the United States, situated in the south-central region of the country. It is the 20th largest state, covering an area of approximately 69,899 square miles, and the 28th most populous with 3.9 million residents. Oklahoma lies partly in the Great Plains and is bordered by six states: Arkansas, Missouri, Kansas, New Mexico, Texas, and Colorado.
Arkansas and Missouri
Oklahoma shares its eastern boundary with the states of Arkansas and Missouri. It is bordered by Missouri on the northeast while Arkansas borders it to the east. When the Arkansas Territory was set up on March 2, 1819, the western boundary was fixed as the 100th degree parallel.
Oklahoma and Kansas share a long border to the north of Oklahoma. Highway 35 runs throughout the two states, connecting Wichita, Kansas' biggest city, with the state of Oklahoma.
New Mexico and Colorado
Oklahoma shares its western boundary at the panhandle with the state of New Mexico. Part of the panhandle also touches the southeast corner of Colorado. Both the borders that Oklahoma shares with Colorado and New Mexico are quite short.
Oklahoma shares its longest border with the state of Texas. The two states share boundary lines to the west and south of Oklahoma. The western boundary was predetermined about 100 years before Oklahoma became a state. It was featured in the treaty of 1819 between the US and Spain and was named as a line at the point of Red River where the 100th meridian crosses the stream and extends to the north.