Route 133 begins as Junction Road at an intersection with US 202 in western Brookfield.

Past Route 25, it becomes Obtuse Road, passing by Center Elementary School, as it continues for another 2.3 miles (3.7 km) to the Housatonic River and Lake Lillinonah.

In Bridgewater, the road turns north and becomes Main Street South as it proceeds towards the town center.

The portion of Old Highway 182 north and east of Brookfield Center was assigned as part of Route 25.

[2] The bridge over the Housatonic River was replaced in 1955 as part of the creation of Lake Lillinonah.