The U.S. Park Police said the cadre of eight Klan members obtained a permit before Saturday's protest rally at the place where the Battle of Antietam was fought Sept. 17, 1862.
"Barack Hussein Obama has been out to destroy America from the beginning," said one hooded speaker, who was not identified. "Our forefathers would have already started something."
The topic of discussion was considered legal free speech by the Parks Police, which issued the necessary permit.
"That's the First Amendment, and that's the beauty of living in America," Sgt. Paul Brooks told The Baltimore Sun.
The newspaper said the rally drew an equally small gaggle of anti-Klan protesters.
David Harty, 61, was the only person in an area designated for counter-demonstrators and wasn't buying into the focus on Obama's policies.
"The KKK is not racist? That's the most ridiculous thing I've ever heard," he said.