Route 29 was the original 1932 designation for today's Route 123 from Norwalk to New Canaan, and today's Route 124 to the state line.
The plan for Connecticut's 2-digit north-south routes mostly followed a pattern, starting at the 20s in the southwest, and extending to Route 95 in the east. The system is more fragmented now (91, 93 and 95 are gone) but much of it remains.
Although early plans for 1932 included Route 27 and possibly Route 23 in Stamford, those highways debuted as route 104 and 137 for consistency at the New York border. As Route 25 was a longer route, out of sequence, this left Route 29 as the lowest number in 1932 following the pattern.
Route 29's original alignment was:
- Riverside Avenue, from US 1 in Norwalk to New Canaan Avenue. This became part of Route 123 after Route 29 was moved, and is now SR 809.
- New Canaan Avenue to Old Norwalk Road in New Canaan. This is part of today's Route 123.
- Old Norwalk Road to Main Street. This is now a town road.
- Main Street to East Avenue in downtown New Canaan; also a town road.
- Main Street and Oenoke Ridge (today's Route 124) to the state line. The road continued in New York using a different number: 394.
At the time, Route 123 started in Darien (following today's Route 124) and intersected Route 29 in downtown New Canaan.
In 1933, work was in progress to relocate Route 29 to a 2-mile "Norwalk - New Canaan Cutoff", which is now called New Norwalk Road. Since the new road bypasses downtown New Canaan to merge with Route 123, it made more sense, for route continuity, for routes 29 and 123 to switch places south of there. (Switching to the south also maintained consistency at the New York border.)
The result: routes 29 and 123 no longer intersected, and Route 29 started in Darien instead of Norwalk. Its new length was 9.44 miles.
In 1945, there was an adjustment in New Canaan where a portion of South Avenue was deleted and a section of Oenoke Ridge Road was added to Route 29. In 1963 a similar switch was made to Cherry Street from South Avenue. I'm sorry that I don't have more details here.
In Westchester County, New York State Route 124 dates back to 1930, originally extending from Pound Ridge to Brewster. In 1966, New York extended the route to the Connecticut state line, connecting with Connecticut's Route 29. To provide consistent numbering, Connecticut renumbered Route 29 to Route 124.
Connecticut changed two other routes in 1966 at the New York line:
- CT 4 to NY 361: a short segment of CT 4 became CT 361
- CT 33 to NY 116: a short segment of CT 33 became CT 116
By 1970, however, New York had eliminated its segment of Route 124 leading to the state line, although the highway still exists further north.