Joe Cress, a cabinet-maker from Abingdon, Va., planned to spend part of his tour looking for the spot near Burnside Bridge where his great-great-grandfather was wounded 135 years ago.
"We all come to see this for different reasons," Cress said.
The association had nine tour buses out Saturday visiting Civil War sites such as Gettysburg, Pa., and South Mountain, volunteer guide John C. Frye said. Two of the buses, with about 47 people in each, toured Antietam Battlefield.
"They already know what happened so what I'm doing is showing where it happened, the terrain," Frye said.
The out-of-towners seemed impressed.
"I would think it's one of your county's treasures," Paul Brinker, of Toledo, Ohio, said on his first trip to the battlefield.
"I think in some ways it's more impressive than Gettysburg ... This seems more like the way it was during the battle," said Mark Ellwein, one of three social studies teachers from Johnson Junior High School in Cheyenne, Wyo., with the group.
"It's just so much easier to understand if you see it," Ellwein's colleague Larry Sturgeon said.
The teachers toted cameras so they could bring back photographs to their classes.
John J. Cahil, of Alexandria, Va., called the area a "paradise for a Civil War buff."
"It's really obvious that a lot has been done to preserve the downtown" in Hagerstown, which could become nationally known as a Civil War history center, Cahil said.
"Hagerstown has done a splendid job. They have been gracious," Dale Fowlkes, of Edmond, Okla., said.
Some members of the association explained their devotion to the memory of the war.
"I think it's really the turning point in American history. It's who we are ... This war was pretty monumental," Cheyenne, Wyo., teacher Tim Holt said.
"We're closer to the war than a lot of people realize," Jim Doherty, of Chevy Chase, Md., said.
Doherty said that when he was growing up in Cincinnati, Ohio, he knew a man in his 80s who had been a Confederate officer.
And when he studied the Civil War in school fistfights between Union and Confederate sympathizers broke out on the playground, Doherty said.
"That's how close we are to these things," he said.
J.D. Pribor, 11, of Madison, N.J., said that while he was interested in the Civil War he wouldn't have wanted to fight in it.
"I wouldn't like to get wounded or killed," he said.
By Saturday night, association president Dennis Frye was proclaiming the anniversary celebration a success.
"This has been a great opportunity to share knowledge and passion for the study of the Civil War," Frye said in a prepared statement. "What a boon for local tourism - tens of thousands of dollars left behind by our guests."