sentences:  In 1540, Spanish colonial expeditions under Hernando de Alarcón and Melchior Díaz visited the area and immediately recognized the natural crossing of the Colorado River as an ideal spot for a city.The Colorado River narrows to slightly under wide in one area.Military expeditions that crossed the Colorado River at the Yuma Crossing include Juan Bautista de Anza (1774), the Mormon Battalion (1848) and the California Column (1862).