Roundtop Mountain Trail | Thermopolis

Spirit Mound Historic Prairie is a significant geological and cultural site located near Vermillion, South Dakota.

Visual Characteristics

The prairie consists of a prominent, solitary hill rising approximately 80 feet above the surrounding Missouri River floodplain. The mound's slopes are covered in native prairie grasses, including Big Bluestem and Indiangrass, with scattered forbs. The summit offers a 360-degree view of the river valley.

Location & Access Logistics

Spirit Mound is situated approximately 4 miles southeast of Vermillion, South Dakota. Access is via County Road 12 (also known as Spirit Mound Road) for 3 miles, then turning south onto a gravel road for 1 mile. A small, unpaved parking area is available at the base of the mound. No public transport services this location.

Historical & Ecological Origin

The mound is a natural geological formation, likely a remnant of glacial outwash or a terrace deposit from the Missouri River. It has been a significant site for the Yankton Sioux tribe for centuries, considered a place of spiritual importance and home to supernatural beings.

Key Highlights & Activities

Visitors can hike to the summit of the mound via a maintained trail. Observation of native prairie flora and fauna is possible. The site is suitable for photography, particularly during sunrise and sunset.

Infrastructure & Amenities

There are no permanent facilities at Spirit Mound Historic Prairie. Restrooms, shade structures, food vendors, and cell phone signal are not available on-site. Visitors should come prepared with water and appropriate gear.

Best Time to Visit

The best time for photography is during the early morning or late afternoon for optimal lighting. The months of June through September offer the most favorable weather conditions for visiting the prairie.

Facts & Legends

According to Yankton Sioux oral tradition, the mound was inhabited by tiny, fierce spirits who would attack any human who approached. Explorer Lewis and Clark documented their encounter with the mound in 1804, noting the local Native American fear of it and their own unsuccessful attempt to find the spirits.

Nearby Landmarks

• University of South Dakota (4.5km Northwest)
• W.H. Over Museum (4.8km Northwest)
• Missouri River (2.0km South)
• Lewis and Clark State Recreation Area (15km Southwest)