 An additional 3.6 mile spur to Colchester is sometimes designated as part of the Air Line trail.At the Massachusetts state line, the trail connects to the Southern New England Trunkline Trail, a 22 mile long trail to Franklin, MA built on the same right-of-way.Since 2018, the town of Portland, CT has also maintained a 2.3 mile portion of the Airline Trail, connecting to the southern end of the state park at the town line with East Hampton.