Ayer’s history began when a mill, used to grind corn for agricultural purposes, was built on what was then part of Groton. Incorporated in 1871, the town was named in honor of Dr. James Cook Ayer, a prominent resident of Lowell who funded the construction of Town Hall.

Ayer’s growth was impacted by the rapid development of railroad transportation during the mid-19th century, serving as a major junction for east-west and north-south rail lines and developing into an important commercial center.

Camp Stevens, home to the 53rd Regiment Massachusetts Volunteers, was established near the Nashua River during the Civil War. This became Fort Devens in World War I, which supported Ayer’s commercial development until 1996, when it was inactivated and reopened as a training area for reserve forces.

Ayer includes numerous industries and a thriving, historic downtown that provides commuter rail service to Boston.