Washington County is included in the Minneapolis-St. Paul-Bloomington, MN-WI Metropolitan Statistical Area.

Early development in the area was on the St. Croix River, which now forms the boundary with Wisconsin on the county's eastern side.

The river provided a waterway to move settlers upstream and to transport logs downstream.

The heavily forested area fostered an early logging and lumber economy.

In 1838 settlers started Dacotah, at the north edge of present Stillwater, at the junction of Brown's Creek and the St.

[4] The creek's name is from the founder of this settlement, Joseph Renshaw Brown.

Brown and other leaders called a meeting (the "Stillwater Convention") on August 26, 1848.

Because of this convention, Stillwater calls itself the “Birthplace of Minnesota.” Congress responded by creating Minnesota Territory effective March 3, 1849.

[9] After the forests were depleted, the economy of Washington County became primarily agricultural.

Late in the 20th century, the population greatly increased with the suburban expansion of St. Paul.

[11] Washington County terrain consists of low rolling hills, sloping to the south and east, with its highest point on the lower west border at 1,053 ft (321 m) ASL.

Washington County voters slightly tend to vote Democratic.

In 63% of national elections since 1948, the county selected the Democratic Party candidate (as of 2020).

Like all counties in Minnesota, Washington is governed by an elected and nonpartisan board of commissioners.