On the east central slope of the Mule Mountains can be found the Copper Queen Mine. In its days of production, (late 19th century - early 20th century) it was the richest copper deposit ever discovered, causing the accompanying town of Bisbee, Arizona to prosper. Under this part of the Mule Mountains are many mining tunnels dug in pursuit of the rich copper ore. Today, Bisbee (also known as the mile-high city, at elevation ) is largely a tourist town and retirement community along the slopes of Tombstone Canyon in the heart of the Mules. There are currently no organized mining operations in effect in the Mule Mountains. Much of the east/southeastern area of the range is private property, owned by Phelps Dodge Corporation.