Tunnel Hill State Trail

The Tunnel Hill State Trail is a bicycle trail running from Eldorado to Karnak, Illinois. The trail runs along the former bed of a part of the Cairo and Vincennes Railroad, a transportation unit led during its early years by Civil War General Ambrose Burnside. The Cairo & Vincennes became a branch line of the Southern Railway before its trail section shut down in the late 1900s.
The northeast end of the trail is in Eldorado, on Trolley Road just north of U.S. Route 45. (). The southwest end of the trail is west of Karnak just off Illinois Route 37 ().
The trail connects to several trails including the River to River Trail; the Illinois southern route of the American Discovery Trail; the U.S. Bicycle Route 76 (part of the TransAmerica Bike Route); and the Trail of Tears National Historic Trail.
The trail is long. The trail is suitable for both hiking and bicycling. The trail surface is crushed limestone. During the summer, the surface is hard packed and easily ridden on a road bicycle. However, at other times of the year, the trail may be soft and is better navigated on a mountain bike or hybrid.
Parking is available at several locations. However, full services (restaurants, lodging, groceries) are only available in Harrisburg and Vienna. There are limited services elsewhere along the trail.