The county is named for James Gaines,[3] a merchant who signed theTexas Declaration of Independence and was born inCulpeper County, Virginia, in 1779. During the 19th century, the land had been occupied solely byComanche and MexicanComancheros, traders who had a thriving business with thePlains Indians. In October 1875, Lt. Bullis, who commanded the24th 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 thePecos River. That November, he came across adraw, 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.[4] Land donated by nonresident landowners became the town ofSeminole, Texas, the county seat. In 1912, a small post office opened up east of Seminole that would later becomeLoop, Texas, named after a local ranch brand. In 1917, theSanta Fe Railroad came through Blythe, Texas, but that name was changed toSeagraves 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-oneoil-producing,cotton-producing, andpeanut-producing county in Texas.[5]
In early 2025, Gaines county became the epicenter of ameasles outbreak that would spread across Texas, New Mexico, Oklahoma and Kansas. The outbreak was declared over as of August 18, 2025,[6] the total number of cases in Texas was 762, with 414 of those cases being reported in Gaines County.[7] 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.[8] This was the highest number of cases in Texas in the last 30 years,[9][10] surpassing the total number of measles cases in the US in 2024,[11] and the death was the first measles death in the US since 2015.[12] The outbreak has been linked to outbreaks in New Mexico, Oklahoma and Kansas.[13] 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 theMMR vaccine.[14][15]
According to theU.S. Census Bureau, the county has a total area of 1,503 square miles (3,890 km2), of which 0.5 sq mi (1.3 km2) (0.03%) is covered by water.[16]
Gaines County, Texas – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
As of the2020 United States census, 21,598 people, 5,812 households, and 4,545 families resided in the county.
As of the 2000census,[23] 14,467 people, 4,681 households, and 3,754 families were residing in the county. Thepopulation density was 10 people per square mile (3.9 people/km2). The 5,410 housing units had an average density of 4 units per square mile (1.5/km2). Theracial makeup of the county was 80.28% White, 2.28% Black or African American, 0.76% Native American, 0.15% Asian, 0.01% Pacific Islander, 14.17% from other races, and 2.35% from two or more races. About 35.77% of the population were Hispanics or Latinos of any race.
Of the 4,681 households, 45.3% had children under 18 living with them, 67.7% were married couples living together, 8.8% had a female householder with no husband present, and 19.8% were not families. About 18.2% of all households were made up of individuals, and 8.6% had someone living alone who was 65 or older. The average household size was 3.07 and the average family size was 3.53.
In the county, the age distribution was 35.0% under 18, 9.50% from 18 to 24, 26.80% from 25 to 44, 18.40% from 45 to 64, and 10.30% who were 65 or older. The median age was 30 years. For every 100 females, there were 97.00 males. For every 100 females 18 and over, there were 94.0 males.
The median income for a household in the county was $30,432, and for a family was $34,046. Males had a median income of $29,580 versus $16,996 for females. Theper capita income for the county was $13,088. About 17.30% of families and 21.70% of the population were below thepoverty line, including 29.2% of those under 18 and 15.7% of those 65 or over.
Most of Gaines County is assigned toSouth Plains College's service area. The portion of the county in Seminole ISD is assigned to theOdessa College service area.[27]
