Grundy County Highway T66 is a north-south highway in the west-central portion of the county. It runs from Grundy County Highway C41, Grand Ridge-Mazon Road, to Grundy County Highway C34, Indian Trail Road, on Gonnam Road. GCH T66 does not pass through any towns in Grundy County. GCH T66 passes through the following townships in Grundy County. Vienna Norman GCH T66 intersects the following highways in Grundy County. Grundy County Highway C41, near near Verona. Grundy County Highway C34, near Seneca.
NB GCH T66 north of GCH C41. NB GCH T66 south of GCH C34.
