Rib Mountain State Park in central Wisconsin preserves a prominent quartzite ridge that long served the Ojibwe and early European explorers as a lookout and navigation landmark. Formed about 1.8 billion years ago, the mountain survived as surrounding softer rock eroded away. In the late 19th and early 20th centuries, it was quarried for quartzite used in sandpaper production, and remnants of that industry remain. Efforts in the 1920s secured its creation as a state park, while Civilian Conservation Corps work in the 1930s improved roads, trails, and winter sports facilities. The park later grew into a regional skiing center while retaining its scenic, geologic, and historic character.