The County was named after Mason Greenlee, an early day mining man. The County is 120 miles long and 20 miles wide it covers 1,837 square miles, and has a population of 8,800. The majority of the land is government owned.

The Forest Service controls 63.5 percent; the Bureau of Land Management controls 13.6 percent; the State of Arizona controls 14.8; and individual or corporate ownership is 8.1 percent.

Greenlee County is located in the southeastern part of the U.S. state of Arizona. As of the 2010 census its population was 8,437. The county seat is Clifton. It is the least populous county in the state of Arizona.

The economy of Greenlee County is dominated by the Morenci Mine, the largest copper mining operation in North America, and one of the largest copper mines in the world.

Morenci Mine is located in eastern Arizona about an hour drive northeast of Safford on the scenic Coronado Trail, this site provides a spectacular view of Arizona's largest mining operation - the Phelps Dodge Morenci mine. The Morenci mine, the largest copper mine in the US, produces over 800 million pounds of copper a year and has moved over 1,000,000 tons in a day! The overlook is about five miles north of the town of Morenci on Highway 191.

The topography consists of desert terrains, river valley, and high mountain ranges. Mining and stock raising are the principal industries. The copper industry has been an important industry in Greenlee County and the State of Arizona for more than 130 years.

In recent years, more people are discovering the many rich and varied scenic and recreational delights to be found here.