Father Kino named the Santa Cruz River which means “Holy Cross” in Spanish back in the 17th century. He was a missionary who brought Christianity to Northern Sonora and Southern Arizona. Over the next twenty-four years he established 24 missions and vistas and set up the foundation for modern agriculture and livestock raising. The length of the Santa Cruz River is approximately 184 miles (296 km) long. The river flows southward from the San Rafael Valley to Mexico then reenters the United States just east of Nogales, Arizona. The Santa Cruz River continues northward from the international border, parallel to the I-19 corridor, past Rio Rico, Tumacacori, Tubac, Green Valley, Sahuarita, Tucson, Marana, and Picacho Peak. The Santa Cruz River goes underground south of Casa Grande and meets with the Gila River.