Washington County comprises the Barre, Vermont micropolitan statistical area.

In 2010, the center of population of Vermont was located in Washington County, in the town of Warren.

[4][5][6] 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.

Vermont which conducted significant trade with British Canada had suffered particularly by passage of the Embargo Act of 1807 during the Jefferson administration.

[19] In 1828, Washington County was won by National Republican Party candidate John Quincy Adams.

From John C. Frémont in 1856 to Richard Nixon in 1960, the Republican Party would have a 104-year winning streak within Washington County.

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.