Tunnel Hill State Trail stretches across the rolling hills and wooded hollows of southern Illinois, following a converted railroad corridor through Johnson, Pulaski, Saline, and Williamson County. This rail-trail runs approximately 45 miles from Harrisburg to the trail’s southern terminus near Karnak, passing through some of the most scenic and least-visited terrain in the state.

The trail’s namesake highlight is a 543-foot tunnel carved through solid rock near the village of Tunnel Hill — one of the few such railroad tunnels in Illinois and a genuinely memorable experience to walk or ride through. The cool, dark passage opens to views of the Shawnee National Forest, and the surrounding landscape shifts from farmland to dense hardwood forest as you move south.

Cycling and hiking are the primary draws, with the crushed limestone surface making the trail accessible for most skill levels. Horseback riding is permitted on a parallel path along certain sections. Birdwatchers will find the corridor productive, particularly during spring and fall migration when warblers move through the forest canopy.

Several small towns along the route — Vienna, Tunnel Hill, New Burnside — offer rest stops with local character. Pack water and snacks, as services are sparse between towns.

Spring wildflower season (April–May) and autumn color (mid-October) are the best times to visit, though summer mornings work well for early riders looking to beat the humidity. Winter riding is possible but check trail conditions after rain, as low sections can stay muddy.

Explore Nearby

• Shawnee National Forest — National Forest in Illinois
• Mary’s River Covered Bridge — Covered Bridge in Illinois
• Land Between The Lakes National Forest — National Forest in Kentucky, Tennessee
• Woodlands Trace National Scenic Byway — Scenic Byway in Kentucky
• Woodlands Trace — Scenic Byway in Kentucky