Washington lies within the Berkshire Hills, and its geography is dominated by October Mountain in the western part of town. The mountain, which is surrounded by the October Mountain State Forest rises to its high plain above the banks of the Housatonic River, falling slowly eastward towards the valley where the Depot Brook (which feeds into a branch of the Westfield River) and the east branch of the Housatonic rise. There are several small reservoirs and lakes throughout the town as well. Along the mountain, the Appalachian Trail crosses through town, and the town is also home to the Bucksteep Manor Cross Country Ski Area.
Route 8 is the only state route through town, passing from Becket to Hinsdale. The nearest interstate highway, Interstate 90 (also known as the Massachusetts Turnpike), is accessible in neighboring Lee. The town has a rail line, operated by CSX and used by Amtrak. The nearest regional airport is Pittsfield Municipal Airport, and the nearest national flights are at Bradley International Airport in Connecticut.
There were 203 households out of which 36.5% had children under the age of 18 living with them, 67.0% were married couples living together, 8.4% had a female householder with no husband present, and 19.7% were non-families. 14.8% of all households were made up of individuals and 6.4% had someone living alone who was 65 years of age or older. The average household size was 2.68 and the average family size was 2.96.
In the town the population was spread out with 26.5% under the age of 18, 5.7% from 18 to 24, 25.2% from 25 to 44, 32.7% from 45 to 64, and 9.9% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 106.1 males. For every 100 females age 18 and over, there were 104.1 males.
The median income for a household in the town was $54,583, and the median income for a family was $55,357. Males had a median income of $40,417 versus $27,143 for females. The per capita income for the town was $23,610. About 4.8% of families and 6.9% of the population were below the poverty line, including 12.5% of those under age 18 and 7.1% of those age 65 or over.
On the state level, Washington is represented in the Massachusetts House of Representatives by the Second Berkshire district, which covers central Berkshire County, as well as portions of Hampshire and Franklin Counties. In the Massachusetts Senate, the town is represented by the Berkshire, Hampshire and Franklin district, which includes all of Berkshire County and western Hampshire and Franklin Counties. The town is patrolled by the Fourth (Cheshire) Station of Barracks "B" of the Massachusetts State Police, and is the southernmost town in that station's patrol area.
On the national level, Washington is represented in the United States House of Representatives as part of Massachusetts's 1st congressional district, and has been represented by John Olver of Amherst since June 1991. Massachusetts is represented in the United States Senate by senior Senator Ted Kennedy and junior Senator John Kerry.
The nearest community college is Berkshire Community College in Pittsfield. The nearest state colleges are Massachusetts College of Liberal Arts in North Adams and Westfield State College in Westfield, and the nearest state university is the University of Massachusetts Amherst.