Samuel Arthur Robertson, railroad developer, engineer, and army officer, the son of Frank Selden and Catherine (Lewis) Robertson, was born at DeWitt, Missouri, on July 10, 1867. He left home at fifteen and went to work on railroad-construction crews. His construction-engineering career began with the Santa Fe Railroad in 1887. He traveled to the Rio Grande valley in 1903 under contract to lay rails for the Gulf Coast lines from Corpus Christi to Brownsville, where he purchased 10,000 acres along the Los Fresnos resaca and organized the San Benito Townsite Company, the San Benito Land and Irrigation Company, and other companies to direct the development of San Benito and the surrounding area. He was a pioneer in developing irrigation districts and building canals and drainage systems in the Valley. To provide access to remote land, Robertson built a network of feeder spurs to connect with the Brownsville Street and Interurban Railroad Company, which he had also promoted and built (see SAN BENITO AND RIO GRANDE VALLEY RAILWAY COMPANY). Locally the network was called "the Spiderweb" and "Sam Robertson's Backdoor Railroad." The system connected eleven communities and brought into being the town of Rio Hondo. In 1910 ice was being shipped from Bay City; Robertson established ice plants in San Benito, Harlingen, and Brownsville to provide ice for refrigerator cars carrying vegetables to city markets. He was the first postmaster of San Benito in 1907 and twice was elected sheriff of Cameron County.
In 1916 he served as a scout for Gen. John J. Pershing's army when it went into Mexico in pursuit of Francisco (Pancho) Villa. On this assignment he was captured, dragged behind a horse, beaten, and left for dead. After recovering, he joined the United States Army, in 1917; he organized and commanded the Sixteenth Engineers, one of the first regiments to go to France. As a lieutenant colonel in 1918, he commanded the Twenty-second Engineers and was promoted to full colonel before his discharge in 1919. He was repeatedly cited for competence in building light rail lines to the front trenches under shell fire. After receiving the Distinguished Service Medal he remained in Europe to rebuild Germany's railway system. He returned to San Benito in 1919 and was elected sheriff of Cameron County in 1922, on the strength of his opposition to an upsurge of Ku Klux Klan activity. After being reelected in 1926 he resigned to pursue his dream of resort development along the Gulf Coast. Robertson was an early advocate of the development of Padre Island; he helped develop Brazos Island with the Valley's first seaside resort, Del Mar, which was destroyed by a hurricane in 1933. His first wife, Adele (Wedegartner), whom he married on March 17, 1901, died on November 21, 1921. He then married Maria Seidler in Vienna, Austria, on December 3, 1922. Neither marriage produced children. Robertson died on August 22, 1938, in Brownsville and was buried in Mission Park Cemetery, San Antonio.