Trout Creek Pass is a mountain pass located in the Rocky Mountains of south-central Colorado in the United States. The pass sits atop the southern end of the Mosquito Range on the Park-Chaffee County line, between South Park (the headwaters of the South Platte River to the east) and the headwaters of the Arkansas River to the west. It is traversed jointly by U.S. Highway 24 (between Hartsel and Buena Vista) and U.S. Highway 285 (between Fairplay and Buena Vista). It is passable by most motorized vehicles and is closed only during severe winter storms. The approach from the north is mild, while the south side has a moderate 5% grade.
Geologically, the pass is located on a fault that runs along the Mosquito Range. Road cuts along the eastern approach to the pass reveal Pennsylvanian black shale and thin gray limestone layers that were laid down prior to the creation of the Ancestral Rockies. These Paleozoic layers were not uplifted during the creation of the Ancestral Rockies approximately 300 MYA and thus were not eroded to the same degree as other areas to the east and west.