Tunnel Hill State Trail is a day-use trail. It is a woody railroad line converted into a bike trail that stretches 45-miles from Harrisburg to Karnak, Illinois.
I’m not an experienced cyclist but I was able to travel the complete trail in a day. Remember to carry food and water.
If you prefer shorter rides, I recommend the trailhead in Vienna that allows comfortable round-trips on the trail—approximately 10 miles north gets you to Tunnel Hill; 13-miles south is the Henry Barkhausen Wetlands Center. With a 2% grade, the trail is comfortable.
Landform changes along the trail. Keep an eye on interpretive signs. Start early; it’s quiet. Be prepared to be with yourself.