Shasta County comprises the Redding, California metropolitan statistical area.

Their population declined in the 1850s due to disease, low birth rates, starvation, killings, and massacres, as White settlers moved in.

[7] The name of the tribe was spelled in various ways until the present version was used when the county was established.

In 1992, the Fountain Fire burned more than 63,000 acres (25,000 ha) and destroyed hundreds of homes and other structures, including large parts of Round Mountain and Montgomery Creek.

[10][11] In 2021, the Shasta County Planning Commission voted unanimously to reject the project's use permit, followed by an appeal to the Shasta County Board of Supervisors that similarly resulted in a 4–1 vote to deny the appeal.

Wildfire risks and firefighting challenges, among other issues, were given as a primary reason for the rejection of the project.

[12] In early 2023, ConnectGen resubmitted its application to the California Energy Commission under Assembly Bill 205 which established a new certification program for non-fossil-fuel powered plants of 50 megawatts or more and related facilities.

According to Willis Linn Jepson, the biota of Shasta County was not explored in a scientific manner until just before 1900.

Until the 1920s, the Southern Pacific Railroad Company owned vast tracts of natural grasslands, but during the 1920s, the railroad sold off much of its grassland holdings, leading to the rapid clearing of brush and large-scale conversion from habitat to agricultural uses.

The economy was shaped by the construction of Shasta Dam and some 60 percent of its registered voters were pro-labor Democrats.

[41] It went Democratic in all but one presidential election from 1932 to 1976, and was one of the few counties in the state to be won by George McGovern.

A 2022 successful recall unseated supervisor, Leonard Moty, Redding's ex-police chief who describes himself as a fiscal conservative and social moderate, after enough signatures were collected to have the election.

[46] County supervisor Kevin Crye met privately with Mike Lindell in Minnesota before the vote.

[48] State and federal law require that voters with disabilities have access to an electronic voting system.

The following table includes the number of incidents reported and the rate per 1,000 persons for each type of offense.