Hanover County was created on November 26, 1720 from the area of New Kent County called St. Paul's Parish. It was named for the Electorate of Hanover in Germany, because King George I of Great Britain was Elector of Hanover at the time.
Hanover County was the birthplace and home of noted American statesman Patrick Henry. And is the home of the Hanover Courthouse, which was the site of the Parson's Cause case in the Virginia Colony, in which attorney Henry argued against taxes levied on preachers by the King. The historic Hanover Courthouse is pictured in the county seal. Hanover County was also the birthplace of politician Henry Clay, author of the Missouri Compromise.
Hanover County at its closest point is only 5 miles from the current city limits of Richmond. However, the Chickahominy River is located at this closest point, which is in the Mechanicsville area. Although the Union Army came within earshot of the bells from Richmond's churches along this river during the 1862 Peninsula Campaign of the American Civil War, no one learned more what an obstacle that river can be than Union General George B. McClellan. He failed in the attempt to get all of his troops across it and overwhelm the smaller-sized Confederate forces defending Richmond, effectively prolonging the War almost 3 more years. Hanover County was the site of a number of Civil War battles, including the Seven Days Battles of the Peninsula Campaign and Battle of Cold Harbor in 1864.
King's Dominion amusement park opened in 1975 and impacted the county's economy.
The incorporated town of Ashland is located within Hanover County.