In the decades following the battle, a few veterans organizations placed commemorative markers to specific units on the battlefield, including the 14th New Jersey (dedicated in 1907), 87th Pennsylvania Infantry, and Vermont markers. In the years that have followed, other monuments have been added, including the Confederate Monument and Maryland Centennial Monument near the Best farm (the site where Union soldiers discovered Robert E. Lee's lost Special Order 191 during the 1862 Maryland Campaign). The National Park Service has since added wayside interpretive markers throughout the park.