Northern Shasta County is located in the forested Cascade Range. Southern Shasta County is located in the agricultural Sacramento Valley.

The Shasta County Farm Bureau reported that the top five crops in 2007 were timber, forest products, hay, stockers and feeders (cattle), and strawberries.

When California became a state in 1850, Shasta County was one of the original twenty-seven counties.

The word Shasta was perhaps derived from the name of an Indian tribe or perhaps from a Russian word for pure. (Russians were early explorers, trappers and settlers in northern California.) The name Shasta was applied not only to the county but also to a river, a town and the spectacular stratovolcano which dominates the landscape of Shasta and Siskiyou Counties.

In 1852, Shasta County ceded territory to its northern neighbor Siskiyou County, and in 1856, it ceded territory to its southern neighbor Tehama County.

Like all of the Central Valley from Redding in the north to Bakersfield in the south, Shasta County is politically, religiously and socially conservative. Its citizens voted decisively for George Walker Bush in 2000 and 2004, for John Sidney McCain III in 2008, and for California Proposition 8 which amended the California Constitution to ban same-sex marriages in 2008.

Shasta County and its neighboring counties are located in the secessionist State of Jefferson.