Oklahoma

I

Introduction

Oklahoma, one of the Midwestern states of the United States, bordered on the north by Colorado and Kansas; on the east by Missouri and Arkansas; on the south by Texas; and on the west by Texas and New Mexico. The Red River forms much of the southern boundary.

Oklahoma is known as the “Sooner State”, a reference to the settlers who arrived before the federal government officially opened the land to settlement. It was admitted to the Union on November 16, 1907, as the 46th state. Oklahoma’s economy has traditionally been dominated by agriculture and mining, but by the early 1990s service industries, government, and manufacturing had grown to become the largest economic sectors. The name of the state is derived from two Choctaw words meaning “red people” and was originally proposed by a Choctaw chief in the 1860s.

II

Land and Resources

Oklahoma has an area of 181,048 km (69,903 sq mi) and is roughly rectangular in shape with a narrow protruding section, the Panhandle, in the north-west. Its extreme dimensions are 357 km (222 mi) from north to south and 747 km (464 mi) from east to west, 269 km (167 mi) of which is formed by the Panhandle. Elevations range from 88 m (289 ft), along the Little River in the south-eastern corner of the state, to 1,516 m (4,973 ft), at the top of Black Mesa in the extreme north-west.

A

Physical Geography

Oklahoma encompasses a diversity of landscapes. It can be divided into six geographical regions: the Great Plains, the Osage Plains, the Ozark Plateau, the Arkansas Valley, the Ouachita Mountains, and the West Gulf Coastal Plain. In the west, confined almost entirely to the Panhandle, is the Great Plains region. Although generally level, this region rises some 914 m (3,000 ft) in elevation from east to west. The central two thirds of the state is occupied by the Osage Plains—a gently rolling region, interrupted only by the Wichita and Arbuckle mountains in the south-west and the Gypsum Hills in the west. In the north-eastern corner of the state is the Ozark Plateau. In contrast to the plains, this is a hilly region. Streams have cut deep valleys in the limestone formations of the plateau and have formed steep bluffs at the junction of the plateau and plains.

To the south of the Ozark Plateau is the Arkansas Valley, an important agricultural region that incorporates the valley of the Arkansas River and the surrounding plains. The Ouachita Mountains, in the south-east, constitute the most rugged region of Oklahoma. The mountains are primarily sandstone ridges, separated by narrow valleys. In the south-eastern corner of the state, lying along the Red River, is the West Gulf Coastal Plain, a relatively flat area with fertile, sandy soils.

Principal rivers are the Arkansas River and its tributaries (including the Cimarron, Neosho, North Canadian, and Canadian rivers) and the Red River and its principal tributary, the Washita. The natural lakes of Oklahoma are small; numerous federal and state dam-building projects have, however, created more than 200 artificial lakes, some of which are extensive. Among the largest are Lake O’ The Cherokees and Texoma, Eufaula, Oologah, Keystone, and Gibson lakes.

B

Climate

The climate of Oklahoma is diverse, changing from a humid subtropical regime in the south-east to a semi-arid continental climate in the west. Summers are hot throughout the state; winters are frequently mild but severe weather does occur, often without warning. The average annual temperature ranges from 13.9° C (57° F) in the west to 18.9° C (66° F) in the south-east. The recorded temperature has ranged most recently from -32.8° C (-27° F) in 1930 to 48.9° C (120° F) in 1943. Powerful storms occur with relative frequency; Oklahoma has more tornadoes per unit area than any other region in the United States.