Thomas Gaines, Farmers' Alliance and independent party leader, was born in Summerville, Georgia, on February 21, 1860, to farmer and carpenter Franklin Gaines and his second wife, Eliza (Graham). He was one of eleven children, eight of whom survived infancy. By mid-1866 the family was living in Cherokee County, Alabama, and by 1884 or 1885 Gaines and his parents were in Comanche County, Texas. His education may have come largely from his mother. His facility with the English language by 1886 suggests he was well educated.
In July 1886 Gaines emerged as a leader in a third-party movement in Comanche County. He was at the time president of a county suballiance of the Farmers' Alliance, the Baggett Alliance, and was called by the editor of the Comanche Town and Country "an intelligent farmer." The independents' county convention nominated Gaines, who had written several letters to the Town and Country, for district clerk and put him on the resolutions committee. Gaines emerged as a major speaker for the independents' party, which came to be called the Human party.
The party's resolutions, which Gaines helped write, reflected the Greenback party's earlier prominence in Comanche County. The new party opposed national banks, railroads, and monopolies in general as antidemocratic and called, among other things, for a national greenback currency loanable by the United States Treasury at low rates to the people of the country; for public lands to be provided to "actual settlers" only, to a maximum of 320 acres per family; and for a distribution of public offices in proportion to their percentage in the state population of "farmers, mechanics, laborers, and other classes." Most of these demands surfaced within days at the Texas Farmers' Alliance state convention at Cleburne and were written into the "Cleburne demands," the first in a long series of demands and platforms in Texas leading to the famous 1892 Omaha platform of the national People's (Populist) party. Members of the Human party also opposed ultimately successful attempts by vigilantes to drive black citizens out of Comanche County during the summer of 1886.
The Human party swept the county election in 1886. Gaines was elected district clerk. In 1887 the supporters of the Human party, as it was called until 1891, when it merged with the Populists, established their own newspaper, the Pioneer Exponent. In 1888 Gaines became editor of the weekly paper, which by 1889 had, according to estimates by the publisher, a circulation of 812. By 1892 Gaines was both editor and publisher, and circulation had climbed to 2,675. The weekly by then was a Populist paper, and lasted as such until 1903. In 1912, as a Democratic paper, it finally merged with the Comanche Chief.
Gaines quickly became an important figure in the Texas Farmers' Alliance, closely allied with the more radical political wing of that organization, which gathered around William R. Lamb, H. S. P. (Stump) Ashby, Harry Tracy, Evan Jones, James Perdue, and William Farmer. He was part of this group's subtreasury campaign, which ultimately separated the Farmers' Alliance in Texas and the South from the Democratic party and pushed the Texas alliance by August 1891 into the People's party. As part of the effort, these antimonopoly greenbackers established two new organizations in April 1891 at the Waco meeting of the state Farmers' Alliance. Gaines was elected chairman of the executive committee of the new Texas Reform Press Association and vice president of the new Texas Citizens' Alliance.
In Dallas on August 17, 1891, the founding convention of the Texas People's party elected Gaines secretary of the convention and chairman of the state executive committee. The same meeting made him head of a state committee charged with developing a "reform" press in Texas. He traveled throughout the state for the next three years helping set up Populist and alliance newspapers. As a capstone to this effort in 1892 he sponsored the effort to make the Fort Worth Texas Advance a state Populist daily paper. The effort failed, but the Advance survived as a weekly in Dallas and was the official paper of the Texas People's party until it merged with the Southern Mercury in 1894. During this time Gaines continued to be active in the Texas Farmers' Alliance.
His constant travel for the alliance and the Populist party in Texas apparently contributed to his early death. He died on May 25, 1894, after a three-week struggle with typhoid fever, "superinduced by fatigue and overexertion." He was at the time serving as secretary of the executive committee of both the Texas Farmers' Alliance and the Texas Populist party. He was also People's party chairman in the Eighth Congressional District. As late as April 30 he had spoken at Ballinger, in Runnels County, with James Harvey (Cyclone) Davis. He was survived by his wife, Mary Semantha (Walker), whom he had married in 1887 in Comanche, and by three children.