Map of the Month: April 2023

Published April 4, 2023
Updated Sep. 26, 2023

Our April Map of the Month is this 1907 map of the American Southwest titled, the ”Greatest Mineral Belt in the World”. The map depicts the breadth of gold, silver, and copper through the mineral belt as it spans over California, Nevada, and Arizona.

The 1907 Great Mineral Belt in the World, with three southwestern states (Arizona, California, Nevada) and a large block of text in the upper right hand corner advertising investment opportunities in mining.
Greatest Mineral Belt in the World, ca. 1907, The American Mines Investment Company.

The American Mine Investment Co. promoted the Arizona Gold Mines Company, who was the operator of the Bimetal Mine in Kingman, Arizona. Bimetal mines were highly profitable at the turn of the 20th century, as they offered two or more metals which could be extracted rather than the typical single ore. Showcasing the profitable mining company, as well as the vast mineral resources of the west, the American Mine Investment Co. created a map to persuade individuals to purchase capital stock in their mining company. 

A centrally aligned paragraph showing the partnership between the American Mines Investment Company and the Arizona Gold Mines Company. A list of the president, secretary, and other managerial members of the American Mines Investment Co. are listed at the top.
The American Mines Investment Company promoting its subsidiary, The Arizona Gold Mines Company

At the time of publication, 1907, mining booms in this corridor of the country were still in full swing. In the years following California’s notable gold rushes of the mid-to-late 19th century, companies and settlements began to populate into the Arizona and Nevada territories. Located between mountains and valleys, differentiated by hachures, miners found luck in the dry, rocky terrain. During the “Boomtown” years, prospecting in the territories pertained mostly to silver and copper, as gold was yet to be appreciable; the longevity of settlements were determined by the harshness of the environment and the mineral opportunities, thus leaving behind ghost towns and successive communities. By the early 1900’s, copper and silver fell short in their economic standing relative to gold, resulting in a second gold rush in the west, revitalizing mining towns in Arizona like Prescott, Congress, Kingman, and Florence. The Bimetal Mine in Kingman, as advertised by the American Mines Investment Co., was worth $70,000 when appraised in 1909, equating to $2,184,368.67 in today’s currency.

Magnification of the south-central mapping portion, showcasing Kingman, Arizona, home to the Bimetal Mine.
Red parallel lines expand across the section of the map, showing Kingman, Arizona within the mineral belt. Red text denotes mines, like the Bimetal Mine, as well as minerals like gold and silver. A thin black line travels west to east irregularly, …

Though the major mining events from the 1880’s to the 1950s drove the economies of Arizona, California, and Nevada, copper’s economic presence has been notable for centuries. Indigenous people of the American southwest mined and traded minerals like copper and silver, establishing trade routes between tribes. Major discoveries from the natives included large silver and gold deposits, like the Lost Escalante Gold Mine near Tucson, Arizona. By the 20th century, it was common for tribes to work with, or establish their own, mining ventures to generate revenue for the people of the reservation. 

While the extent of the mineral belt runs through California and Nevada, the richest concentration and widest extent of the belt rests in Arizona. The southwestern United States was subjected to intense volcanism 50-80 million years ago, which created hot magma beneath the Earth’s surface. When the magma began to cool, it released water from the melt and created copper. Though all three states recorded in the American Mines Investment Company’s map experienced volcanism, Arizona’s dry climate and mountainous terrain has preserved and exposed rich deposits, making it a large part of the greatest mineral belt in the world!

We hope you enjoyed our April Map of the Month! This map and its accompanying details are now available to view in Drawer 3 of our 3D Explorer application. To request a high resolution scan of this map or to schedule an appointment to view the collection in person, please submit a service request to the Map and Geospatial Hub. 


     -Paityn Schlosser, Map and GIS Assistant