Corner Bridge

After the Great Bridge washed out at the Fordway in 1699, Billerica was generally content to not replace it. Since it was the only crossing of the Concord River that was convenient for Chelmsford residents to reach Boston, they sued to have it rebuilt. Billerica compromised by building the Corner Bridge, which provided a much more convenient crossing for its own residents. A robust neighborhood grew up on the east side of the bridge, called The Corner. In 1873, the wooden bridge was replaced with iron, which gradually turned rust-colored, earning it the name "The Red Bridge".

At the February 1920 Town Meeting, it was unanimously voted to straighten 3A by building a new bridge running north-south instead of east-west. The town spent $10,000, with the County, State, and even Federal governments contributing. The contract was awarded to James H. Fannon and construction began in May 1920. It opened for travel in Spring 1921.

In 1942, the old iron bridge was demolished as part of a war salvage project. The main stone support for the old bridge can still be seen in the middle of the river.