As of the census[3] of 2000, there were 347 people, 157 households, and 108 families residing in the unorganized territory.

The racial makeup of the unorganized territory was 99.14% White, 0.29% Native American, 0.29% Asian, and 0.29% from two or more races.

27.4% of all households were made up of individuals, and 8.9% had someone living alone who was 65 years of age or older.

Williamsburg was located in the southern part of Piscataquis County, 17 miles north-east of Dover-Foxcroft.

The area was first settled by people of European descent during the first decades of the 19th century and was incorporated as a town in 1820.

[4] The 1900 census showed that Williamsburg had a population of 117, the smallest of all incorporated towns in the county.