In 1935, Route 71A was created, following a "new road" from Route 71 in Berlin to the the intersection of Kensington Ave. and Arch St. in New Britain, for a length of 3.03 miles. This extends 0.11 miles beyond present-day Route 71A on the same alignment. High Road in the area is the older alignment. The "new road", formerly known as Cat Hole Pass Road, is now the northern section of Chamberlain Highway.

In 1949, Route 71A's official length was decreased 0.01 mile to 3.02 miles, but was essentially unchanged.

The 1961 Highway Reclassification recommendations included extending Route 71A into downtown New Britain to reunite with Route 71. In 1962, this was partially done, as Route 71A was extended along Arch Street. In 1969, however, transfers of 0.73 miles of this route from town to state were still under arbitration. By the early 1970s, Route 71A was at its longest: 4.71 miles, extending along Arch St, Main St, and E. Main St to Stanley St, where Route 71 was at the time.

On Sept. 11, 1974, the city of New Britain and the state signed an agreement to turn over Route 71A to city maintenance, truncating it at the Berlin town line, just north of what is now SR 571. On Mar. 12, 1979, this was to have taken effect; but on Sept, 25, 1981, this was rescinded, pending determinations involving the planned Route 9 freeway extension through the city. This left the northern terminus at W. Main St, SR 555, just south of the Route 72 freeway, for a length of 3.98 miles.

Starting in 1990, the disposition of Arch Street was another source of friction between the state and city. The state planned to resurface the street, then still part of Route 71A, and turn it over to local maintenance. The city, however, wanted more extensive work done on pipes and utility lines, some of which dated back 100 years.

The city and state eventually agreed to share the cost. In May 1995, a $7.5 million reconstruction project for Arch Street began. Later in 1995, Route 71A was truncated back to Buell St, where it ends today.