The town of Ayer, although not incorporated until 1871, became an important railroad hub in the 1840s, with the completion of both north–south and east–west railroad routes that crossed just southwest of the present downtown area. During the American Civil War, a military camp was established to the south (later to become Fort Devens). The downtown area began to develop most significantly after incorporation in 1871 and a fire in 1872 that destroyed many earlier structures. The north side of Main Street, opposite the rail yards of the junction, is where this new commercial development was focused.
