From 1748 to 1751, three Spanish missions (San Francisco Xavier de Horcasitas, San Ildefonso, and Nuestra Señora de la Candelaria) and a presidio (San Francisco Xavier de Gigedo) were built within five miles of this site by missionaries, soldiers, and resident Indians. The Spaniards' goals were to Christianize and civilize the numerous Indian tribes in the area and to establish a presence. During this period, a rock dam and a system of acequias (canals) were constructed just east of Apache Pass to irrigate the fields of one of the nearby missions. All of these improvements were abandoned in 1755 due to a combination of disease, drought, and Indian troubles. Apache Pass, named by the Spanish, was a gravel bar crossing on the San Gabriel River in this general area that was used successively by Americans Indians, explorers, settlers, and local farmers and ranchers.