- Southern Terminus:
- Roosevelt Drive (CT 34) in Seymour
- Northern Terminus:
- Bradleyville Road (CT 63) in Middlebury
- 15.92 miles
- New Haven
CT 188 begins at Roosevelt Drive (CT 34) by the Housatonic River in Seymour. The first section, Squantuck Road, runs northeast for about a mile to a traffic circle at the northern terminus of Great Hill Road (CT 334). CT 188 turns north onto Rockhouse Hill Road, which changes names to become Quaker Farms Road. It runs north to Southbury, where Quaker Farms Road ends at Southford Road (CT 67). The two routes are multiplexed for one block to the northwest, and then CT 188 splits off onto Strongtown Road, which runs north to an interchange with the Yankee Expressway (I-84). Beyond the interchange, Strongtown Road curves to the east and changes names to become Southford Road. In Middlebury, Southford Road ends, and CT 188 follows Middlebury Road (CT 64) for a few blocks before splitting off again onto West Street, which becomes Whittemore Road. It runs to the southeast, crossing the Yankee Expressway (I-84) again, although this time with no interchange. Shortly thereafter, it ends at Bradleyville Road (CT 63).