In the later 1820s trappers, hunters, and mountain men like James Ohio Pattie, Antoine Leroux, and Pauline Weaver became some of the first Anglo-Americans to venture through Arizona, in search of beaver pelts. Such men would in turn guide the Army of the West and the Mormon Battalion through the state in 1846 and 1847 during the Mexican War.

After the war ended in 1848, much of what is now the Southwest became U.S. property, and in 1850 a huge area that included Arizona and New Mexico became the New Mexico Territory. In 1854 the land between the Gila River and the Mexican border—Southern Arizona, basically, some 29,644 acres—was added to the territory through the Gadsden Purchase at a price of about $10 million.

Beginning in 1849 and lasting for several years afterward, thousands of Americans passed through Arizona headed for gold and glory in California. Those hard-rock, hard-luck miners would return east to the state a few years later in search of the gold and silver most of them had failed to find on the coast. Several boundary, land, railroad, and scientific surveys of Arizona and the West during the 1850s brought this far corner of the continent greater attention and interest from the East.

It was the increasing mining activity in the state that, among other factors, led President Lincoln to establish the Arizona Territory in 1863, disconnecting it from the huge conglomerate of land called New Mexico. The capital was established at Prescott, in the state’s mineral-laden midlands, and the East’s economic exploitation of the land, albeit on a much smaller scale than it would eventually become, commenced.

During the Civil War, Tucson was a Confederate hotbed for a time before being occupied by the U.S. Army. After the Civil War ended, immigration and exploration of the Southwest picked up considerably. Still, when John Wesley Powell completed the first river-run through the Grand Canyon in 1869, the population of the territory was less than 10,000 persons.

Indeed, for may years before and after the Gadsden Purchase and the Civil War, Tucson remained a sparsely populated outpost in a far, forgotten corner of the world. But settlers trickled in over the coming years, spurred here to cure their tuberculosis, or in search of treasure, adventure, science, or cheap land. Despite this, the territory remained a wild and dangerous place for most. The Apache, Navajo, and other tribes didn’t feel they should have to give up the land they had conquered to white settlers, many of whom were looking to get rich quick by exploiting the land and then leave.

From 1871 until the final surrender of Geronimo in 1886, the U.S. Army fought a brutal war with the Apache and other tribes. The Apache finally beaten, the territory moved one step closer to large-scale settlement and development.

From 1867 to 1877 Tucson was the capital of the Arizona Territory, until that distinction was handed over for good to the growing, largely American town of Phoenix about 100 miles north in the Salt River Valley. On March 20, 1880, the Southern Pacific Railroad arrived in Tucson and completely transformed the city, bringing in more people and materials than ever before. By 1882, with a population of about 8,000 persons, the once-isolated adobe village could boast gas lights and even a few telephones.