The Tumacácori Mission is located in the upper Santa Cruz River Valley of southern Arizona. The mission was established in 1691 (oldest in Arizona) by Father Kino and the Spaniards for the purpose of converting Indians to Christianity. The Spaniards attracted Indians to the Mission by growing food and offering it to them. The Mission had a 6,700 acre orchard and about 5,000 cattle.

The O’odham Indians had the first contact with the Spaniards at the Mission. Occasionally they ate too much and their stomachs exploded; the O’odham were used to periods of plenty interspersed with periods of hunger, but the mission provided plenty of food all year long. The Apache Indians raided the mission and killed seven O’odham. Many more O’odham were killed by European diseases.

In 1821, Mexico gained its independence and did not want to support the missions anymore. The priests were expelled and Apache raids increased. In 1849 gold seekers stayed at the mission. In the late 19th and early 20th centuries, rumors of lost Jesuit gold led to raids of the mission by treasure hunters, who ruined large parts of the mission.

By proclamation of President Theodore Roosevelt in 1908, the old mission ruins of Tumacacori were made a National Monument.