Route 209 is Bantam Lake Road, which passes to the west of Bantam Lake.

The Route 109/209 intersection in Morris is one of the few in Connecticut that resemble the branching numbering system in Pennsylvania and Indiana. The 209 number arises from the Connecticut practice of choosing a new number "rhyming" with a route's older designation (in this case, 109) where possible: SR 722 becomes Route 222, SR 864 becomes SR 664, and so on.

CT 209 History

In the 1920s, Route 209 was part of the old State Highway 310, an L-shaped road leading from Bantam to Thomaston along today's Route 209, and part of today's Route 109.

In 1932, SH 310 became Route 109.

In 1963, Route 109 was straightened out, and the north-south portion became Route 209.