The first American to make a mark on Mariposa was John C. Fremont, soldier, explorer, and (later) presidential candidate. In 1847, while California was still Mexican territory, Fremont instructed his acquaintance, Thomas O. Larkin, to purchase the Santa Cruz ranch, a piece of property near San Jose. For some reason, Larkin purchased the Rancho Las Mariposas instead, to Fremont’s annoyance, since this worthless land was over one hundred miles from the nearest settlement, had no farms or ranchlands, and was inhabited by hostile Indians. The discovery of gold the following year, however, completely altered Fremont’s reaction. The gold rush was on and settlers flooded the area. Mariposa turned out to be at the southern end of the mother lode, and in addition to the town of Mariposa, a number of other settlements sprang into being, such as Agua Fria (briefly the Mariposa county seat in 1850 and 1851), Hornitos, Indian Gulch, Bear Valley, Coulterville, Mount Bullion (Princeton), and Bagby.
As the placer gold played out during the 1850s and early 1860s, hard rock quartz mining, organized by companies and worked by employees (who often lived in company housing and patronized company stores) replaced most of the thousands of individual miners and their tents, shanties, and the entrepreneurial businesses that had served them. “Less colorful, more orderly”, is how one expert describes the change in communities that survived. A dwindling number of individuals, however, continued working small claims and mines.
Although the gold rush frenzy faded, it was responsible for roads being built and communities established, so that now settlers could turn to ranching, farming, and the small businesses serving them, along with the mines. The Railroad built along the Merced River to El Portal enabled various large scale enterprises. In fact during the 1920s close to 2,000 people lived and worked in the Merced River Canyon between Bagby to El Portal.
The Yosemite Lumber Company logged sugar pines from the slopes bordering Yosemite from 1912 until 1942. Faint signs of the inclines (tracks going straight up the side of the hills) are visible today in El Portal. Smaller logging operations continued elsewhere in Mariposa County through the 1950s. The Yosemite Portland Cement company quarried limestone from 1928 until 1944. A surviving building and sheds still exist across the river from Highway 140, about two miles west of Savage’s Trading Post at the South Fork of the Merced. In the 1930s and 1940s a barium mine and crushing plant operated in El Portal. Also in the 1930s, due to an increase in the price of gold, many mines resumed or stepped up the level of their operations, and individuals again took to the river and creeks to do placer mining