- Southern Terminus:
- Boston Post Road (US 1) in Old Saybrook
- Northern Terminus:
- CT 9 in Middletown
- 28.24 miles
CT 154 has two distinct sections. The first is a loop to the south of US 1 in Old Saybrook. This section has a number of different names. The majority of it is designated as a scenic route, which is very much deserved. There are numerous breathtaking views of Long Island Sound along this section, as well as a causeway over South Cove. While the entirety of CT 154 is officially a north/south route, this section is signed as an east/west route, and many of the signs along this section give only the route number without a compass direction. This avoids confusion that could result due to the section's semicircular route.
Between the two sections CT 154 is multiplexed with US 1 along Boston Post Road. The second section begins at Boston Post Road (US 1) in Old Saybrook. It is a north/south route called Middlesex Turnpike and Saybrook Road that runs near the Connecticut River, parallel to the CT 9 expressway. It ends at an interchange with CT 9 in Middletown.