- Southern Terminus:
- I-91 and Foxon Boulevard (CT 80) in New Haven
- Northern Terminus:
- CT 2 in Glastonbury
- 36.88 miles
- New Haven, Middlesex, Hartford
CT 17 begins in New Haven at the junction of I-91 and Foxon Boulevard (CT 80). It runs diagonally to the northeast as Middletown Avenue and New Haven Road to Durham. It then runs north through Durham and Middletown as Main Street and South Main Street. In Middletown, it is multiplexed with CT 9 for a couple of exits and then crosses the Connecticut River to Portland on the Arrigoni Bridge, multiplexed with CT 66. On the other side, it continues east along Marlborough Street and Portland Cobalt Road, still multiplexed with CT 66. It then splits off and runs north to Glastonbury as Gospel Lane and Glastonbury Turnpike. In Glastonbury, a short limited-access highway called the Glastonbury Expressway carries CT 17 to its northern terminus at CT 2.