Ajo is a town because of mining. According the the Ajo Chamber of Commerce website’s history page (http://www.ajochamber.com/explore/history-of-ajo/),

On the way to silver mines near Magdalena, Sonora, Tom Childs, Sr. and his party chanced upon the Ajo area in 1847 and stopped to mine the ore they found. Soon the Arizona Mining & Trading Company, formed by Peter M. Brady, a friend of Childs, worked the rich surface ores, shipping loads around Cape Horn [and] smelting in Swansea, Wales, in the mid 1850s. The mine closed when a ship sank off coast of Patagonia. Childs and other prospectors worked claims here; long supply lines and the lack of water discouraged large mining companies…

A wily promoter, A.J. Shotwell, enticed John Boddie of Missouri to help set up the St. Louis Copper Company in 1890s. Shotwell organized the rescue [of] Copper Company when bankruptcy threatened. This became the Cornelia, then the New Cornelia, named after Boddie’s first wife.

“Professor” F.L McGahan and Shotwell introduced the so-called vacuum smelter that supposedly channeled each type of molten ore to different spigots and ran perpetually on the initial fuel. Mcgahan [sic] conveniently slipped away from the demonstration model in Los Angeles –it exploded when been [sic] tested.

The first to develop the Ajo area profitable [sic] was John Campbell Greenway…He became general manager of the Calumet and the Arizona Mining Company. Dr. L.D. Ricketts and Greenway developed a leaching method to process the carbonate ore overburden. Greenway also located the well that still provides water to Ajo and directed the construction of the Plaza, the community’s focal point. Calumet and Phelps Dodge merged in 1931 and the mine became the new Cornelia Branch of Phelps Dodge, managed by Michael Curley…

Ajo continued as the quintessential southwestern mining town, with occasional strikes and shutdowns, until 1983. The strike that began in July that year crippled the community with acrimony on both sides. Though the mine struggled on with non-union labor, copper prices plummeted and so did Ajo. Mining stopped in 1985. P[helps] D[odge] remained a presence in the community but sold much of its holdings, including the Plaza and the company housing. The remaining mines [sic] property is now owned by Freeport-McMoran [sic] Gold and Silver, Inc., which merged with Phelps Dodge in 2007.

According to http://www.mindat.org/loc-3370.html, the New Cornelia

is a huge open pit operation  (about 3,000 feet long and nearly 2,000 feet wide) at 750 feet deep. Haulage was by internal railroad installed in the pit. Total production from 1917 through 1972 amounts to some 350,000,000 tons of ore…Higher grade ore was mined in the early years and lower grade ore in more recent years.

I picked up a sheet of “Mine Facts” at the Ajo visitor center. The question and answer format gives a lot of information about the mine.

Tell us about the open pit?

First, three green hills were leveled from 1916 to 1930. Each bench of the pit is forty feet deep. In all, it is 1 1/2 miles wide and 1 1/4 miles across. Currently it is 1100 feet deep.

And what about the lake at the bottom?

The water, about 90 to 100 feet deep in places, is spring fed…The color is from the copper sulfite.

How does this mine compare with others?

At one time the New Cornelia was the largest producer of copper in Arizona. In 1959 it was the third largest open-pit mine in the United States and the second largest copper producer in Arizonza.

There is a mine lookout and visitor center (open October through May) on Indian Village Road. I went out there early one morning before it got too hot. There was an elderly man standing outside the visitor center. When I asked him if the lookout was open, he told me it was. He told me a lot about himself and the mine.

He first came to Ajo with his father in 1949. He worked at the mine in the maintenance department for over 32 years. He told me that when he worked in the mine, equipment was expensive and men were cheap. He said that’s how thing are in China now, which is why there’s more mining going on in China than the U.S. He said there’s still copper in the mine, but it’s low grade, and right now it’s not profitable for Freeport-McMoRan to extract it. However, Freeport-McMoRan gets tax breaks on the mine, so it’s in the company’s best interest to hang on to the mine until it is again profitable to extract the copper.

Here’s more from the “Mine Facts” sheet:

Is the mine closed?

Yes, mining operations shut down in 1984 and the smelter closed in 1985. At its peak about 3000 were employed.

Did the mine close because of labor unrest?

No. The mine continued operating during and after the strike of 1983. Falling copper prices resulted in the closure of many Arizona mines in 1985.

Can the mine ever be re-opened?

A large quantity of low-grade ore remains. It depends upon the demand for copper and the plans of the owner. When the mine closed it was capable of producing 40,000 tons of copper annually.

The open pit mine is massive. It’s one of those things that is so big, my brain has trouble processing it. (Mine brain seems to have particular trouble with gigantic things made by people. I can look at a mountain or a giant sequoia and think, that’s HUGE, and my brain grasps it, understands it. But when I look at, say, the enormous football stadium at UT Austin or the New Cornelia Mine, I can feel my brain struggling to comprehend how such a thing could possibly exist.)

The wall of each terrace is 40 feet tall. Each “bench” (the flat part of the terraces) is 40 feet wide. When the mine was open, trains chugged around on those terraces.

(From the “Mine Facts” sheet:

How was the ore hauled up?

Tracks were laid down on the terraces, and then ore cars were loaded by steam shovels.)

I cannot put into words how big this mine is. Unfortunately, my photos don’t do justice to massiveness of the open pit. Trust me, it’s fantastic, in an Oh, no, what have we done? sort of way.

I took all of the photos in this post.