Pilares is on the Rio Grande a mile from Quinn Creek and eight miles southwest of Gettysburg Peak and San Carlos in southwest Presidio County. At the site have been a presidio, a penal colony, and a silver ore smelter. In 1750 the Spanish viceroy designated Pilares a presidio and in 1775 a military and penal colony. The soldiers, as well as the convicts marooned there, worked the farms. The source of the silver ore and the time of its extensive smelting at Pilares is unknown.
Pilares was a stronghold of criminals during the border raids in the second decade of the twentieth century. On May 21, 1915, five Texas Rangers pursued a number of Mexican bandits from Pilares into the Mexican mountains to recover stolen horses and mules. After a running gunfight on May 23, the bandits escaped. The next day the rangers again went after the robbers. Caught in a narrow canyon by Mexican fire and greatly outnumbered, the rangers attempted to retreat. Rangers Trollingers, Cummins, and Craighead escaped. Rangers Sitters and Hulen, separated from the others and cut off from any escape route, were killed.
In 1914 an agricultural revolution came to the farming communities of the Rio Grande valley above the entrance of the Río Conchos. Cotton was introduced as a money crop, and irrigation projects were built in each community. Pilares completed a new gravity ditch that irrigated about 300 acres of farmland. In 1982 Pilares remained a small farming community on the Rio Grande and an unimproved road.