Prior to the California Gold Rush, the area now known as Plumas County was inhabited by the Native American Indians known as the Mountain Maidu. Living in small groups, they gathered roots, berries, grasses, seeds, and acorns, supplementing these staples with large and small game and fish. Their existence was suddenly disturbed in the spring of 1850 when a flood of gold seeking miners poured into the canyons and valleys of the region in search of a fabled “Gold Lake.”

Overnight, mining camps sprang to life. Rivers were turned from their beds, ditches were dug to bring water from distant sources to the diggings, and the land was turned upside down. A sizable Chinese population took up residence here and remained until the early 1900s, when, with the decline in mining, most left the area. The North, Middle and South forks of the Feather River, named in 1820 by Spanish explorer Captain Louis Arguello as the Rio de las Plumas, were the primary sites of early mining activity with many smaller camps located on their tributaries. Over the next five decades gold mining remained the main industry of the county.

            In 1850, the famous African-American mountain man, James P. Beckwourth, discovered the lowest pass across the Sierra Nevada and the following year navigated a wagon trail for California bound emigrants from western Nevada, through Plumas County, to the Sacramento Valley. Several years later, in March of 1854, Plumas County was formed from the eastern and largest portion of Butte County with the town of Quincy chosen as the county seat after a heated election against rival Elizabethtown. In 1864, a large part of northern Plumas County was carved off to form present-day Lassen County. Following this, Plumas County annexed a small portion of Sierra County, which included the town of La Porte.

            In the late 1850s, Greenville came into existence as a mining and farming community at the head of Indian Valley; Chester, near Lake Almanor, was born as a result of cattle and dairy ranching, the damming Big Meadows and the lumber potential from the timber stands blanketing the area. Soon after the turn of the century, and with the construction of the Western Pacific Railroad in 1910, Portola came into existence. With the railroad for transportation, the timber industry began to emerge as the primary economic force in the county. Until that time lumber was milled strictly for local use. Finished lumber could now be shipped nationwide from Plumas forests. The timber industry contributed enormously to the growth and prosperity of Plumas County and though curtailed greatly, it continues to do so to this day.

            Coeval with the railroad's construction up the Feather River canyon came some of the earliest tourists to the county. Resorts and lodges popped up at intervals along the "Feather River Route" to accommodate fishermen, hikers and sightseers. The last passenger train ran in 1970 and the line is now devoted to freight traffic only. In 1937, the Feather River Highway, touted as an "all weather route," was completed through the Feather River canyon from Oroville to Quincy, linking Plumas County year round to the Sacramento Valley.