Jackson, named after Colonel Alden Jackson, was founded in 1848 around a year-round spring. Settlement of the region by American pioneers was stimulated by the discovery of gold in the Sierra foothills around 1848. The settlement was named for a local lawyer who was liked by miners named Alden Appola Moore Jackson. Although Amador County was an important mining center, its County seat of Jackson was not typical of the early gold camps. The camp grew quickly, as besides being a popular mining spot, it was also a convenient stopping place on the road from Sacramento to the Southern Mines. The camp became an important supply and transportation center for the neighboring towns, and by 1850 the population had reached an estimated 1,500. Jackson grew first as a watering hole for cattle, then as one of the earliest and most durable of the Mother Lode's hardrock mining areas.
Placer mining gave out by the 1860s, replaced by hard rock mining. One of the town's most prominent historical landmarks, the Kennedy Mine, began operation in 1860; at the time of its closure during World War II in 1942, it was the deepest gold mine in North America, at 1802 meters; (5912 feet).