A Spanish mine was developed near Ajo in 1750, called the "Old Bat Hole". The mineshaft was on a sixty-degree angle and about every ten feet a layer of mesquite logs four feet long and three feet wide was placed to serve as rest stations for the men carrying the ore. The miners had rawhide buckets strapped to their backs to carry up the rock. Unfortunately, it was abandoned due to Indian raids. Then in 1847, the first American set up his mine in the Ajo area. Tom Childs came upon a deserted mine and found high-grade native copper. 

Ajo became the first copper mine in Arizona. Then the Ajo Copper  Company organized in 1854. During this time pack mules carried the ore to Yuma, where it was shipped down the Colorado River. Then it was sent on by boat around the Cape Horn to Swansea, Wales for smelting. However, Ajo did not flourish. The mining town remained relatively unnoticed, until the beginning of the 1900's. The reason for its sudden popularity was the development of new ore-refining techniques, which made mining in Ajo much easier and more profitable. One of the first companies in Ajo was the New Cornelia Copper Company.  John Campbell Greenway started the company, along with some partners.  The mine was named after one of the partner’s wives.  Eventually, the town began to prosper. 

A downtown plaza was built in 1917. The plaza reveals the Spanish architecture that has influenced the town, due to its proximity to the Mexican border. Then in 1931, the company was sold to Phelps Dodge. The company had over 1,000 men working in the mine, until 1986 when it closed down. Phelps Dodge sold many of its homes in town to retirees.

Today you will find the town is a perfect retirement spot. As for the name of the town, it is hard to pinpoint. Some say it is from the Spanish word garlic, which Mexican miners found in the area. Others say it came from the Papago Indian word for paint because this was the area the Indians collected copper minerals to make the paint for their bodies.