Westminster lies on both the Old Boston Turnpike and the historic Mohawk Trail at the foot of Mount Wachusett, the highest peak in Central Massachusetts. In the 18th century, the unsettled territory that is Westminster was designated to be given as payment to soldiers that fought in the French and Indian War.
Originally called "Narragansett Number Two" in deference to the Native American tribes who lived in the region, Westminster became a district in 1759 and was fully incorporated in 1770. Its name is rooted in traditions of the minister in old England.
A significant portion of the land within the town’s boundaries (including Leominster State Forest) is owned by the Commonwealth, and its many lakes and rivers create a large watershed for the Nashua River.