|Washington County, Vermont|
Washington County Courthouse
Location in the U.S. state of Vermont
Vermont's location in the U.S.
|• Total||695 sq mi (1,800 km2)|
|• Land||687 sq mi (1,779 km2)|
|• Water||8.2 sq mi (21 km2), 1.2%|
|• ( 2016)||58,504|
|• Density||85.8/sq mi (33.1/km2)|
|Time zone||Eastern: UTC−5/ −4|
Washington County is a county located in the U.S. state of Vermont. Named after George Washington, its county seat is the city of Montpelier, the least populous state capital in the United States, and the most populous municipality is Barre.  As of the 2010 census, the population was 59,534,  making it the third-most populous county in Vermont, but the third-least populous capital county in the United States after Hughes County, South Dakota and Franklin County, Kentucky. If Carson City, Nevada and Juneau, Alaska was treated as counties, Washington County would be the fifth-least populous capital county.
Washington County is one of several Vermont counties created from land ceded by the state of New York on January 15, 1777 when Vermont declared itself to be a distinct state from New York.    The land originally was contested by Massachusetts, New Hampshire, and New Netherland, but it remained undelineated until July 20, 1764 when King George III established the boundary between New Hampshire and New York along the west bank of the Connecticut River, north of Massachusetts and south of the parallel of 45 degrees north latitude. New York assigned the land gained to Albany County.   On March 12, 1772 Albany County was partitioned to create Charlotte County,  and this situation remained until Vermont's independence from New York and Britain.
Washington County was originally established as Jefferson County in 1810 from parts of Caledonia County, Chittenden County, and Orange County and organized the following year. 
In 1814 it was renamed to Washington County. The name change occurred after the Federalists took control of the Vermont Legislature from the Jeffersonians. Vermont which conducted significant trade with British Canada had suffered particularly by passage of the Embargo Act of 1807 during the Jefferson administration. 
- Lamoille County – north
- Caledonia County – northeast
- Orange County – southeast
- Addison County – southwest
- Chittenden County – northwest
|U.S. Decennial Census
1790–1960  1900–1990 
1990–2000  2010–2016 
As of the 2010 United States Census, there were 59,534 people, 25,027 households, and 15,410 families residing in the county.  The population density was 86.6 inhabitants per square mile (33.4/km2). There were 29,941 housing units at an average density of 43.6 per square mile (16.8/km2). 
Of the 25,027 households, 28.2% had children under the age of 18 living with them, 47.1% were married couples living together, 10.0% had a female householder with no husband present, 38.4% were non-families, and 29.7% of all households were made up of individuals. The average household size was 2.28 and the average family size was 2.81. The median age was 42.3 years. 
The median income for a household in the county was $55,313 and the median income for a family was $66,968. Males had a median income of $45,579 versus $38,052 for females. The per capita income for the county was $28,337. About 5.9% of families and 10.5% of the population were below the poverty line, including 13.8% of those under age 18 and 7.5% of those age 65 or over. 
Following the Democrats victory in 1964, the county went back to voting for Republican candidates for another 20 year winning streak starting with Richard Nixon in 1968 and ending with George H. W. Bush in 1988, who became the last Republican presidential candidate to win the county.
- List of counties in Vermont
- List of towns in Vermont
- National Register of Historic Places listings in Washington County, Vermont
- "Find a County". National Association of Counties. Retrieved 2011-06-07.
- "State & County QuickFacts". United States Census Bureau. Retrieved December 30, 2013.
- "Centers of Population by State: 2010". United States Census Bureau. Retrieved May 6, 2014.
- Slade, William, Jr., comp. Vermont State Papers: Being a collection of Records and Documents Connected with the Assumption and Establishment of Government by the People of Vermont, Together with the Journal of the Council of Safety, the First Constitution, the Early Journals of the General Assembly, and the Laws from the Year 1779 to 1786, Inclusive. Middlebury, 1823. P. 70-73.
- Van Zandt, Franklin K. Boundaries of the United States and the Several States. Geological Survey Professional Paper 909. Washington, DC; Government Printing Office, 1976. The Standard Compilation for its subject. P. 64.
- Williamson, Chilton. Vermont in Quandary: 1763-1825. Growth of Vermont series, Number 4. Montpelier: Vermont Historical Series, 1949. PP. 82-84; map facing 95, 100-102, 112-113.
- Slade, William, Jr., comp. Vermont State Papers: Being a collection of Records and Documents Connected with the Assumption and Establishment of Government by the People of Vermont, Together with the Journal of the Council of Safety, the First Constitution, the Early Journals of the General Assembly, and the Laws from the Year 1779 to 1786, Inclusive. Middlebury, 1823. pp.13-19.
- Van Zandt, Franklin K. Boundaries of the United States and the Several States. Geological Survey Professional Paper 909. Washington, DC; Government Printing Office, 1976. The Standard Compilation for its subject. P. 63.
- New York Colonial Laws, Chapter 1534; Section 5; Paragraph 321)
- "Vermont: Individual County Chronologies". Vermont Atlas of Historical County Boundaries. The Newberry Library. 2008. Retrieved June 30, 2015.
- "And They Called The County Washington". Central Vermont Chamber of Commerce. Central Vermont Magazine. Summer 1988. Retrieved October 10, 2016.
- "2010 Census Gazetteer Files". United States Census Bureau. August 22, 2012. Retrieved June 29, 2015.
- "Population and Housing Unit Estimates". Retrieved June 9, 2017.
- "U.S. Decennial Census". United States Census Bureau. Retrieved June 29, 2015.
- "Historical Census Browser". University of Virginia Library. Retrieved June 29, 2015.
- Forstall, Richard L., ed. (March 27, 1995). "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Retrieved June 29, 2015.
- "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. April 2, 2001. Retrieved June 29, 2015.
- "DP-1 Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data". United States Census Bureau. Retrieved 2016-01-20.
- "Population, Housing Units, Area, and Density: 2010 - County". United States Census Bureau. Retrieved 2016-01-20.
- "DP03 SELECTED ECONOMIC CHARACTERISTICS – 2006-2010 American Community Survey 5-Year Estimates". United States Census Bureau. Retrieved 2016-01-20.
- Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Retrieved 2018-03-26.
- National Register of Historic Places listing for Washington Co., Vermont
- Life in Washington County Documentary produced by Vermont Public Television