Johnson County, the one hundred twenty-ninth county organized in the state, was created from Emanuel, Laurens, and Washington counties in 1858.  It had been part of the land ceded in 1773 to form the headright county of Washington.  The name honors Hershel V. Johnson, a former Georgia governor and senator.  Wrightsville, the county seat, was named for John B. Wright, a pioneer resident.

Johnson is said to be the first county in the state to enforce prohibition.

 
The county's irregular southern boundary is due to a personal feud between an influential resident of the town of Adrian and his county commissioner in Emanuel County.  Vowing that he wouldn't live in the same county with the commissioner, the townsman persuaded his friends in the General Assembly to change the boundary of Johnson County.  They obliged him and put part of the town in Johnson.

 

The Jefferson/Johnson county line follows the route of the Old Sunbury Road, one of the longest thoroughfares of its time.  Laid out in the 1790s, it connected the coastal port of Sunbury with Swainsboro, Sparta, and Greensboro.

 

A greatly outnumbered group of Confederate home guards held off a wing of Union General Sherman's invading army for two days at Bells Ferry in November, 1864.  They retreated only when ammunition ran out.