Oklahoma

Oklahoma is the 20th-largest state in the United States, covering an area of 69,898 square miles (181,035 km), with 68,667 square miles (177847 km) of land and 1,281 square miles (3,188 km) of water. It is one of six states on the Frontier Strip, and lies partly in the Great Plains near the geographical center of the 48 contiguous states. It 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 and near-west by Texas.

The western edge of the Oklahoma panhandle is out of alignment with its Texas border. The Oklahoma/New Mexico border is actually 2.1 to 2.2 miles east of the Texas line. The border between Texas and New Mexico was set first as a result of a survey by Spain in 1819. It was then set along the 103rd Meridian. In the 1890s, when Oklahoma was formally surveyed using more accurate surveying equipment and techniques, it was discovered that the Texas line was not set along the 103rd Meridian. Surveying techniques were not as accurate in 1819, and the actual 103rd Meridian was approximately 2.2 miles to the east. It was much easier to leave the mistake as it was than for Texas to cede land to New Mexico to correct the original surveying error. The placement of the Oklahoma/New Mexico border represents the true 103rd Meridian.

Cimarron County in Oklahoma's panhandle is the only county in the United States that touches four other states: New Mexico, Texas, Colorado and Kansas.Oklahoma is between the Great Plains and the Ozark Plateau in the Gulf of Mexico watershed,generally sloping from the high plains of its western boundary to the low wetlands of its southeastern boundary. Its highest and lowest points follow this trend, with its highest peak, Black Mesa, at 4,973 feet (1,516 m) 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, OK, which dips to 289 feet (88 m) 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 half contains three.Oklahoma has four primary mountain ranges: the Ouachita Mountains, the Arbuckle Mountains, the Wichita Mountains, and the Ozark Mountains. Contained within the U.S. Interior Highlands region, the Ozark and Ouachita Mountains mark the only major mountainous region between the Rocky Mountains and the Appalachians. A portion of the Flint Hills stretches into north-central Oklahoma, and near the state's eastern border, Cavanal Hill is regarded by the Oklahoma Tourism & Recreation Department as the world's tallest hill; at 1,999 feet (609 m), it fails their definition of a mountain by one foot.

The semi-arid high plains in the state's northwestern corner harbor few natural forests; the region has a rolling to flat landscape with intermittent canyons and mesa ranges like the Glass Mountains. Partial plains interrupted by small mountain ranges like the Antelope Hills and the Wichita Mountains dot southwestern Oklahoma, and transitional prairie and woodlands cover the central portion of the state. The Ozark and Ouachita Mountains rise from west to east over the state's eastern third, gradually increasing in elevation in an eastward direction.

More than 500 named creeks and rivers make up Oklahoma's waterways, and with 200 lakes created by dams, it holds the highest number of artificial reservoirs in the nation. Most of the state lies in two primary drainage basins belonging to the Red and Arkansas rivers, though the Lee and Little rivers also contain significant drainage basins.

Forests cover 24 percent of Oklahoma and prairie grasslands composed of shortgrass, mixed-grass, and tallgrass prairie, harbor expansive ecosystems in the state's central and western portions, although cropland has largely replaced native grasses. Where rainfall is sparse in the western regions of the state, shortgrass prairie and shrublands are the most prominent ecosystems, though pinyon pines, red cedar (junipers), and ponderosa pines grow near rivers and creek beds in the far western reaches of the panhandle.

Marshlands, cypress forests and mixtures of shortleaf pine, loblolly pine and deciduous forests dominate the state's southeastern quarter, while mixtures of largely post oak, elm, red cedar (Juniperus virginiana) and pine forests cover northeastern Oklahoma.The state holds populations of white-tailed deer, mule deer, antelope, coyotes, mountain lions, bobcats, elk, and birds such as quail, doves, cardinals, bald eagles, red-tailed hawks, and pheasants. In prairie ecosystems, American bison, greater prairie chickens, badgers, and armadillo are common, and some of the nation's largest prairie dog towns inhabit shortgrass prairie in the state's panhandle. The Cross Timbers, a region transitioning from prairie to woodlands in Central Oklahoma, harbors 351 vertebrate species. The Ouachita Mountains are home to black bear, red fox, grey fox, and river otter populations, which coexist with a total of 328 vertebrate species in southeastern Oklahoma. Also, in southeastern Oklahoma lives the American alligator