Plains, the county seat of Yoakum County, is on U.S. Highway 82 thirteen miles east of the New Mexico border and fifty-nine miles southwest of Lubbock in the central part of the county. The area was first settled by a family named Miller, who claimed land as a homestead in the late 1800s. In 1905 the W. J. Luna family moved to Sulphur Draw which extends through the site of Plains. Luna founded and named the town and donated a lot in the townsite to each voter. He also donated land for the Yoakum County Cemetery and the Plains Cemetery, in which his wife, Mary, was the first person to be buried. Luna established a store and in 1906 a post office, to which mail was routed through Gomez.
When the county was organized in 1907, Plains was designated the county seat. The Yoakum County News, edited by Neil H. Bigger, began publication in 1910 in Plains. In 1931 Mrs. Dovie Moreland began to publish and edit the Yoakum County Review, which was consolidated with the Plains Record in 1961. Mrs. Marion McGinty and other early citizens of Plains maintained a bookshelf for the public, moving the books to different homes for accessibility to everyone. The women joined others and petitioned the commissioners' court to establish a county library at Plains and a branch library at Denver City. By 1922 Plains had a drugstore run by Preston McGinty, a grocery store run by L. N. Clayton, a real estate office run by J. J. Kendrick, and a general store. In 1937 a Mr. Ridner opened a barbershop, and a Mrs. Read opened a beauty shop in the room next to it.
Sulphur Springs Draw, through which a flowing stream once ran, is now a park. The springs, like all of the springs in the area, have dried up because of the pumping of underground water for irrigation and city use. With the springs has gone much of the wildlife in the area. Since the discovery of oil in 1936, both the town and the county have grown steadily, although the lack of a railroad has kept the area from growing as rapidly as surrounding counties. Plains had a population of 150 in 1939, 480 in 1947, and 1,500 in 1980. In 1990 the population was 1,422. By 2000 it was 1,450. Agriculture and oil account for most of the taxable revenue of Plains, although employment fluctuates with the growing season. The Yoakum County Clinic opened in 1959 and provides all services except hospitalization. A "bonus shack," which was a tiny shack that settlers had to occupy a specified time in order to obtain title to land, can still be seen in Plains. It was built in 1903 and is maintained by the Tsa Mo Ga Study Club as a museum.