Bartow County was created from the Cherokee lands of the Cherokee County territory on December 3, 1832, and named Cass County, after General Lewis Cass (1782–1866), Secretary of War under President Andrew Jackson, Minister to France and Secretary of State under President James Buchanan,[3] who was instrumental in the removal of Native Americans from the area.

Cass had supported the doctrine of popular sovereignty, the right of each state to determine its own laws independently of the Federal government, the platform of conservative Southerners who removed his name.

The American Civil War first entered Bartow County on April 12, 1862, in the form of "The Great Locomotive Chase": As a result of the Western & Atlantic Railroad’s (W&A RR) strategic war time value, Union soldiers boarded and stole a train named "The General".

Their plan was to take the stolen train north toward Chattanooga, Tennessee, destroying bridges, parts of the railroad, and telegraph lines along the way.

Bartow County was profoundly affected by the Civil War: an estimated one out of three Bartow County soldiers died during the war as a result of wounds received, diseases caught, and, in one case, as a result of a train accident.

At the end of the Civil War, many residents were financially insolvent, the county seat was "in ruins", the transportation networks were severely damaged, and the citizens were starving due to several consecutive years of crop failures.

[6] Prior to the Civil War, Bartow County's social order, and that of the South as a whole, was dominated by "a sense of white intra-class unity that rested upon a shared notion of racial supremacy.

"[7] Post-Civil War, during Reconstruction, that world-view was challenged, creating a period of racial tension.

[6] And when black families petitioned Bartow County for better educational and vocational opportunities, some local whites responded with violence, including but not limited to Ku Klux Klan activity.

The peninsula between the two major arms of the lake is home to Red Top Mountain State Park, east-southeast of Cartersville and just southeast of the dam.

As of the 2010 United States Census, there were 100,157 people, 35,782 households, and 26,529 families living in the county.

Barack Obama won a small minority of votes in the county, at 23.5 percent, that same year.