The KKK's application was rejected by the Georgia Department of Transportation on grounds that only "civic-minded institutions in good standing" can participate, The Atlanta Journal-Constitution reported.
The Klan has a history of violence against blacks and minority groups.
Harley Hanson, who calls himself the exalted Cyclops of the Real of the International Keystone Knights of the KKK, filed the application jointly with his wife.
In the document Hanson said he could deliver at least six volunteers to clean up a road in Union County, Ga. He listed the group's address as a post office box in Blairsville, Ga.
Executive Director Debbie Seagraves of the Georgia ACLU, confirmed that her organization is representing Hanson but added "we're still working on the strategy."