Exempt are the cities of Hephzibah and Blythe, in southern Richmond County, which voted to remain separate.

The county is named for Charles Lennox, 3rd Duke of Richmond, a British politician and office-holder sympathetic to the cause of the American colonies.

It was formed from a portion of the colonial Parish of St. Paul after the Revolution disestablished the Church of England in the (former) Royal Province of Georgia.

However, in every presidential election from 1952 to 1988 which did not have Georgian Jimmy Carter on the ballot, the county backed the Republican candidate for president.

1928 was an exception to this rule with Herbert Hoover beating Al Smith handily due to anti-Catholic sentiment.