Gaines County is a county in the U.S. state of Texas. As of the 2020 census, its population was 21,598. The county seat is Seminole. It gained national attention in 2025 for a major outbreak of measles.
History
The county is named for James Gaines, a merchant who signed the Texas Declaration of Independence and was born in Culpeper County, Virginia, in 1779. During the 19th century, the land had been occupied solely by Comanche and Mexican Comancheros, traders who had a thriving business with the Plains Indians. In October 1875, Lt. Bullis, who commanded the 24th Infantry Regiment, encountered a large group of Indians at Cedar Lake. Lt. Bullis captured them for food, supplies, utensils, and buffalo hides. Then, Col. Shafter established a camp at Cedar Lake and continued to scout the area as far south as the Pecos River. That November, he came across a draw, where he discovered more than 70 wells reaching levels 4 to 15 feet deep. This area became a regular place to trade goods.
In 1887, the northern part of the county was occupied by the Mallet Ranch. The foreman, Dave Ernest, sold the ranch to a merchant from San Antonio, who used the land for driving cattle towards Kansas. On October 24, 1905, Gaines County became an organized county in Texas. Land donated by nonresident landowners became the town of Seminole, Texas, the county seat. In 1912, a small post office opened up east of Seminole that would later become Loop, Texas, named after a local ranch brand. In 1917, the Santa Fe Railroad came through Blythe, Texas, but that name was changed to Seagraves after the company discovered they already had a town by the same name located on the line.
A large population addition to Gaines County came in 1977 when a group of conservative German speaking "Russian" Mennonites from Mexico arrived to start farming and ranching. In 2005, Gaines County became the number-one oil-producing, cotton-producing, and peanut-producing county in Texas.
In early 2025, Gaines county became the epicenter of a measles outbreak that would spread across Texas, New Mexico, Oklahoma and Kansas. The outbreak was declared over as of August 18, 2025, the total number of cases in Texas was 762, with 414 of those cases being reported in Gaines County. Spreading across 34 additional counties, two deaths of children were reported. Typical of measles outbreaks, the burden of disease is heavier on the unvaccinated and children. This was the highest number of cases in Texas in the last 30 years, surpassing the total number of measles cases in the US in 2024, and the death was the first measles death in the US since 2015. The outbreak has been linked to outbreaks in New Mexico, Oklahoma and Kansas. The vaccination exemption rate in Gaines County is among the highest in the state, with nearly one in five incoming kindergarteners in the 2023–2024 class not having received the MMR vaccine.
Geography
According to the U.S. Census Bureau, the county has a total area of , of which (0.03%) is covered by water.
Major highways
- 20px U.S. Highway 62
- 25px U.S. Highway 180
- 25px U.S. Highway 385
- 20px State Highway 83
- 20px State Highway 115
- 20px State Highway 214
Adjacent counties
- Yoakum County (north)
- Terry County (north)
- Dawson County (east)
- Martin County (southeast)
- Andrews County (south)
- Lea County, New Mexico (west)