Thomas A. Rodríguez, one of five Tejanos elected to the state legislature in the nineteenth century, was born on December 31, 1839, in Tamaulipas, Mexico, to Mariano and María Josefa Rodríguez. His father had served as an officer in the Spanish army and later in the Mexican army during the war of independence from Spain. His mother was a native of San Antonio. Rodríguez was educated at the University of Northern Pennsylvania. He later returned to Texas, where he held a position as a clerk in the offices of the county clerk and tax collector in Bexar County before the Civil War. When war broke out Rodríguez joined the Confederate Army as a lieutenant of an independent company; he was later placed in the Rio Grande-based company headed by Santos Benavides and served as an adjutant and commissary. At the end of the war he returned to Bexar County, worked as a deputy in the collector's office, and was later elected assessor and collector for the county. He was appointed to the Board of School Examiners in San Antonio in 1867. That year he married María J. Rodríguez, a distant relative, in San Antonio; they had three children. Sometime after his marriage, Rodríguez took his family to Pleasanton, Atascosa County, where they owned property. The 1880 census cites Rodríguez's occupation as foreman.
He apparently became active in politics in Atascosa County and regularly attended state, county, and district Democratic conventions. He was elected to serve in three state legislatures, including the Seventeenth, Twenty-third, and Twenty-seventh. In his first campaign for the House of Representatives, he reportedly defeated a third-party candidate by a majority vote of 6,000. As a member of the Seventeenth Legislature, Rodríguez represented the Seventy-eighth District, which included Atascosa, Karnes, Live Oak, Wilson, and San Patricio counties. In the Twenty-third and Twenty-seventh legislatures he represented the Ninetieth District, which encompassed his original constituency except for San Patricio County. He served on various House committees, including Irrigation, Agricultural Affairs, Town and City Corporations, Federal Relations, County Government and County Finances, and Privileges and Elections. The House Journal from the Twenty-third Legislature shows that he introduced two judicial bills. One called for penitentiary sentences of eight to fifteen years for individuals convicted of horse, ass, and mule thievery. The other moved criminal and civil jurisdiction from the county court to the district court. Rodríguez apparently died in early 1903, two years after his final legislative term. An "In Memoriam" was read into the House Journal record on April 9, 1903. The tribute recalled him as "a noble and worthy citizen and patriotic son."