Photo by Justin Meissen via Atlas Obscura

Minnesota was logging country in the late 1800s, and as a result, most of the state’s old-growth trees were cut down. At present, only 2% of trees in Minnesota’s forests are considered old-growth, but there is an extraordinary place known as The Lost 40, where the elderly giants survive en masse. It’s an area of 144 acres of pure old-growth forest, and its survival until now is due to a mapping error.

In 1882, a surveying and mapping error made loggers believe that the entire section of the forest was underwater, so they passed through it. This area, which is actually located in the Chippewa National Forest, was therefore never logged, and the trees that were growing then continue to grow now.
The tradition of leaving the Lost 40 untouched has remained, and the forest section is still thriving as a result. There is nowhere else in the Midwest like the Lost 40, since most of the trees in other forests are much younger than this swath of centenarians growing in the Midwest.

Story via: Atlas Obscura, where you can find more photos and a small map.