On Thursday, National Geographic published an article highlighting several old maps of United States' national parks featured in Harvard's new exhibit, "The Land Remains: A Century of Conservation in America’s National Parks." Honoring the 100th anniversary of the formation of the National Parks Service, these maps capture spectacular moments of U.S. history and the discovery and preservation of some of the nation's most gorgeous natural wonders. One of the included maps tells the story of how one man illustrated every regiment present at Gettysburg just shortly after the battle took place.

The position of every regiment of both the Union and Confederate armies during all three days of the battle of Gettysburg are detailed on this incredibly detailed map of the battlefield from 1863. Credit: Library of Congress

John Badger Bachelder arrived at Gettysburg before the soldiers’ bodies were buried. He spent the next 84 days studying the battlefield by horseback and filling notebooks with the accounts of injured soldiers from both sides of the battle. He even took some of the wounded back to the scene so they could point out their positions and recount what had happened.

The striking panoramic map of Gettysburg (above) that Bachelder based on this work is meticulously detailed. It depicts where every Union and Confederate regiment stood during each of the three days of battle in July, 1863. His work was so accurate, in fact, that Bachelder was put in charge of deciding where most of the 1,320 physical monuments and markers would be placed in what is now Gettysburg National Military Park.

Check out a couple more maps below and then head over to National Geographic to read more.

When the mountaineer and cartographer Bradford Washburn visited the Grand Canyon in 1969, he was disappointed by the lack of large-scale maps that had enough detail to be useful for hikers. So with support from the National Geographic Society and the Museum of Science Boston, Washburn made this beautiful map of the “Heart of the Grand Canyon,” published in 1978. Credit: National Geographic Society

The renowned Hayden Survey that scouted the Yellowstone area at the behest of Congress in 1871 produced the first detailed maps of the area’s geothermal wonders. This map shows a portion of the Upper Geyser Basin. Credit: Betsy Mason/U.S. Department of the Interior

Feature image via Library of Congress