Gustavo (Gus) A. Guerra, sheriff and Democratic party leader in Starr County politics, was born in Roma, Texas, on March 10, 1890, to Virginia Cox and Manuel Guerra. He married Hortensia Longoria, and they had two daughters. He attended Roma schools and then St. Louis College (now St. Mary's University). From 1911 to 1913 he managed his father's store. From 1915 to 1918 he worked as assistant cashier of the First State Bank and Trust Company of Rio Grande City. In 1918 a federal grand jury indicted him for filing a false affidavit to escape the draft. He assisted in Liberty Loan drives and the Red Cross during World War I.
Guerra held political office for over thirty years. He served as county tax collector in 1913–14, as both county sheriff and tax collector in 1918, as tax collector in 1920, and as sheriff from 1920 to 1948. In 1929 and 1933 five members of the Guerra family, called the political bosses of Starr County, held office in the county. In 1933 José T. Canales organized a party in the county to oppose the Guerras, but the effort was short-lived, and the Guerras remained in power until the 1940s. In 1946 the family still owned most of the property in Starr County.
Guerra was one of six Tejanos included in Texas Democracy, a history of the Democratic party published for the Texas Centennial in 1936. He was also included in the Primer Anuario de los Habitantes Hispano-Americanos de Texas, a Mexican-Texan Who's Who published in 1939. He was a Catholic and member of the Woodmen of the World. He died in 1953.