Map - Lamoille County, Vermont (Lamoille County)

Lamoille County is a county located in the U.S. state of Vermont. As of the 2020 census, the population was 25,945, and it is the third-least populous county in Vermont. Its shire town (county seat) is the town of Hyde Park, while Morristown is the county's largest town by population as well as its main commercial center. The county was created in 1835 from portions of Orleans, Franklin, Washington, and Chittenden Counties and organized the following year.

The area was buried in a mile of ice during the ice age. As the ice melted, Lake Stowe was formed. When the ice melted completely, the water from the lake ran out through the Lamoille River valley.

This area was long occupied by the Algonquian-speaking indigenous Abenaki people and their ancestors. During French colonization of what is now Canada, fur traders began to trade with the Abenaki. There were also French who settled here, coming down from the settlements in Quebec, and named the Lamoille River. The French later enlisted the Abenaki as allies in the frontier raiding and wars with English colonists in the lower New England colonies. For decades there was no border and peoples passed freely through this area.

After the American Revolutionary War and Vermont's admission as a separate state, the county was settled in the 19th century by American migrants from other parts of New England and French-Canadian immigrants from across the border. Some developed small farms. Some came to work in the asbestos mine on Belvidere Mountain, which operated into the 20th century. Some gradually moved to other counties where there were cotton mills, weaving cotton from the South both before and after the Civil War. In the United States, many of the French immigrants were forced to accept anglicization of their names, such as New City for Villeneuve, or Senton for St. Onge. Some of their descendants have reclaimed their family's original names.