Billerica is a town in Middlesex County, Massachusetts, United States. The population was 40,243 according to the 2010 census.
In the early 1630s, a Praying Indian village named Shawshin was at the current site of Billerica.In 1638, Massachusetts Bay Governor John Winthrop and Lt. Governor Thomas Dudley were granted land along the Concord River in the wilderness which was called Shawshin by the local Native Americans. (Today, Shawshin is commonly spelled Shawsheen; see Shawsheen River.) Most of the settlement was to take place under the supervision of Cambridge; however, financial difficulties in the colony prevented this from taking place, and the issue of settling Shawshin continued to be deferred. Finally, in 1652, roughly a dozen families from Cambridge and Charlestown Village, later Woburn, had begun to occupy Shawshin as well.Wishing to replace the foreign-sounding Shawshin with a name more familiar, the settlers chose the name Billerica, likely because some of the families living in the settlement came originally from the town of Billericay in Essex, England. The town was incorporated as Billerica in 1655, on the same day as neighboring Chelmsfordand nearby Groton. The original plantation of Billerica was divided up into four towns, Billerica, Bedford,Wilmington, and Tewksbury, sometime during the colonial era.