Route 29 was the original 1932 designation for what is now Route 124 in Darien and New Canaan. It was the lowest number in the state's geographical system of clustering nearby route numbers: the 30s (and 29) in Fairfield County, moving eastward to the 90s in Windham and New London counties. The system is more fragmented now (91, 93 and 95 are gone) but much of it remains.

As a bit of trivia, some lower route numbers (definitely 27, probably 23) were also planned for 1932 but not used.

Route 29 was commissioned in 1932, and is shown following parts of routes 123 and 124 from Norwalk to the New York state line:

• Riverside Avenue, from US 1 in Norwak to New Canaan Avenue. This became part of Route 123 after Route 29 was moved, and is now SR 809.
• New Canaan Avenue and Norwalk Road, to East Avenue in New Canaan. This is part of today's Route 123.
• East Avenue (probably) to Main Street, New Canaan (now part of Route 106)
• Today's Route 124 to the state line. The road continued as New York state route 394.

By 1934, Routes 29 and 123 had switched places south of New Canaan, with Route 29 starting in Darien instead of Norwalk. Its length at that time 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 that year 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.