Originally a part of neighboring Chelmsford, West Chelmsford soon grew large enough to sustain its own governance, and was officially incorporated as Westford on September 23, 1729.

In the late 18th and early 19th centuries, Westford primarily produced granite, apples, and worsted yarn. The Abbot Worsted Company was said to be the first company in the nation to use camel hair for worsted yarns. Citizens from Westford also had some notable involvement in the Revolutionary War. Westford Minutemen were alerted by efforts of Samuel Prescott who alerted Acton, to the southeast towards Stow.

Paul Revere's son attended Westford Academy and a bell cast by Revere graces its lobby today. A weather vane made by Paul Revere sits atop the Abbot Elementary school.

By the end of the American Civil War, as roads and transportation improved, Westford began to serve as a residential suburb for the factories of Lowell, becoming one of the earliest notable examples of suburban sprawl. Throughout the 20th century (and with the invention of the automobile), Westford progressively grew, continuing to serve as residential housing for the industries of Lowell, and later, Boston.

In the 1960s, the town was home to one of the research sites supporting Project West Ford.

By the 1970s, with the advent of the 128 Technology Belt, Westford began to act as a suburb for high-tech firms in Burlington, Woburn, and other areas, and later became a center of technology itself.

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