Westminster is a town in Windham County, Vermont, United States. The population was 3,016 at the 2020 census. It is also the first capital of the Republic of Vermont. It borders the state of New Hampshire.

Westminster is Vermont’s oldest existing town and was chartered in 1735 by the Province of Massachusetts Bay and was called New Taunton or Township Number One. The town did not have any permanent settlers in the area until 1751. New Hampshire settlers came in and the town was later incorporated in the Province of New Hampshire on November 9, 1752, becoming the third chartered town for New Hampshire west of the Connecticut River. When the British government recognized the Province of New York’s claims to what is now Vermont, New York moved its Court of Common Pleas for Cumberland County to Westminster in 1772. It was the site of the Westminster massacre in March 1775, in which two men were killed attempting to prevent New York provincial officials from exerting their authority over the area in the long-running dispute over the New Hampshire Grants. On January 15, 1777, a group of Vermonters met in the Westminster courthouse to declare the independence of the Republic of New Connecticut (later renamed the Republic of Vermont).

According to the United States Census Bureau, the town has a total area of 46.1 square miles (119.5 km), of which 46.1 square miles (119.3 km²) is land and 0.04 square mile (0.1 km) (0.06%) is water.

Westminster is crossed by Interstate 91 (Exit 5 serves the town), U.S. Route 5, Vermont Route 121 and Vermont Route 123.

The New England Central Railroad has track rights through the town. Amtrak’s Vermonter passenger rail line runs through Westminster but does not stop in town. The closest stations are Bellows Falls to the north and Brattleboro to the south.

As of the census of 2000, there were 3,210 people, 1,246 households, and 843 families residing in the town. The population density was 69.7 people per square mile (26.9/km²). There were 1,412 housing units at an average density of 30.6 per square mile (11.8/km). The racial makeup of the town was 97.73% White, 0.40% Black or African American, 0.28% Native American, 0.22% Asian, 0.34% from other races, and 1.03% from two or more races. Hispanic or Latino of any race were 0.69% of the population.

There were 1,246 households, out of which 34.6% had children under the age of 18 living with them, 55.5% were married couples living together, 8.8% had a female householder with no husband present, and 32.3% were non-families. 24.4% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.06.