Route 57 was commissioned in 1932. Its original route was 20.33 miles long, extending from US 1 in Westport to Route 34 (now Route 302) in Newtown. The only other posted highways it intersected were Route 105 in Weston and Route 58 in Redding.

Here are the details, from south to north:

• Main Street, from US 1 to Canal St. This is now a local street.
• Main Street, from Canal Street to Weston Road. This is also today's Route 57.
• Weston Road (today's Route 57) leading to the Newtown Turnpike
• Newtown Turnpike (much of this is Route 53 today) leading to Route 58 in Redding
• Hopewell Road, Poverty Hollow Road, and Key Rock Road, to end at Route 302

At the time, the Georgetown Road segment of today's Route 57 was part of Route 53.

In 1949, Route 57's official length decreased 0.43 miles, to 19.90 miles; I don't have details on the change.

In 1954, Route 57 was shortened and its northern end was moved. The Newtown Turnpike segment became SR 725. The segment north of Route 58 was removed from the state highway system. Route 57 was redirected along Georgetown Road, replacing Route 53, to end at Redding Road (the redefined Route 53) near US 7. Its length was now 9.51 miles, coincidentally the same as today's.

The original 1954 alignment at the Redding - Weston town line followed Covenant Lane and Old Georgetown Road. (In 1986 those roads were known as "Old Route 57".) In 1959 the project to relocate Route 57 here was announced, and eventually took place.

On Mar. 29, 1963, several highways in the area were rearranged. Route 53 was relocated to follow some of the Newtown Turnpike segment of old Route 57. Former Route 53 leading north from Georgetown became part of Route 107.

In Georgetown, Route 57 was extended a short distance west, overlapping with Route 107, to reach US 7. In Westport, Route 57 was moved from the segment of Main Street leading to US 1, and instead followed Canal Street and King's Highway North to end at Route 33.