According to the United States Census Bureau, the town has a total area of 26.4 square miles (68.3 km²), of which, 26.1 square miles (67.6 km²) of it is land and 0.3 square miles (0.7 km²) of it (0.99%) is water. Charlemont is located in the western part of the county, with a small portion making up the western county line with Berkshire County. The town is bordered by Rowe to the northwest, Heath to the northeast, Colrain and Shelburne to the east, Buckland to the southeast, Hawley to the southwest, and Savoy and Florida to the west. Charlemont is 18 miles west of Greenfield, 45 miles north-northwest of Springfield, and 106 miles west-northwest of Boston.
Charlemont's eastern border is marked by the junction of the North River and the Deerfield River, the latter flowing westward through town. The majority of town lands lie north of the river, except for a strip along the entire Hawley town border. The town is surrounded by the eastern Berkshires, with the western part of town being dominated by Todd Mountain and the Mohawk Trail State Forest. Several other lower peaks dot the land north and town of the river, including Bald Mountain and Westfield Mountain north of the center of town, and, just over the Hawley town line, Mount Peak and Mount Institute. There are also several brooks through town, with Mill Brook lying near the town center (the site of a covered bridge).
Much of the length of the Deerfield in town is followed by the Mohawk Trail, also known as Route 2. Near the center of town, the road also junctions with, and shares a short, 0.6-mile concurrency with Route 8A. Along the southern bank of the river, a stretch of the Guilford Rail System leads fright trains from Greenfield towards the Hoosac Tunnel in neighboring Florida, towards New York. The nearest interstate, Interstate 91, is several miles to the east along Route 2. The town lies at the westernmost point of the "Campus West" line of the Franklin Regional Transit Authority (FRTA) bus line, with scheduled stops at the Academy and at Avery's Store. The nearest regional bus and air service is in Greenfield and North Adams, the nearest Amtrak rail service is in Pittsfield, and the nearest national air service is at Albany International Airport in New York.
There were 524 households out of which 30.7% had children under the age of 18 living with them, 50.8% were married couples living together, 12.2% had a female householder with no husband present, and 32.6% were non-families. 25.2% of all households were made up of individuals and 8.0% had someone living alone who was 65 years of age or older. The average household size was 2.52 and the average family size was 2.99.
In the town the population was spread out with 25.1% under the age of 18, 8.0% from 18 to 24, 29.1% from 25 to 44, 26.3% from 45 to 64, and 11.6% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 96.8 males. For every 100 females age 18 and over, there were 94.1 males.
The median income for a household in the town was $46,548, and the median income for a family was $50,962. Males had a median income of $37,500 versus $26,667 for females. The per capita income for the town was $19,577. About 6.5% of families and 10.4% of the population were below the poverty line, including 10.9% of those under age 18 and 4.2% of those age 65 or over.
Charlemont employs the open town meeting form of government, and is led by a board of selectmen. The town has its own police, fire and public works departments. The town's library, Tyler Memorial Library, is connected to the regional library network. Charlemont lies halfway between hospitals in North Adams (North Adams Regional Hospital) and Greenfield (Franklin Medical Center). Greenfield is also the site of most of the county's public services, courthouses and the county jail.
On the state level, Charlemont is represented in the Massachusetts House of Representatives as part of the First Berkshire district, which includes the northern portion of Berkshire County as well as several towns in northwest Franklin County. In the Massachusetts Senate, the town is part of the Berkshire, Hampshire and Franklin district, which includes all of Berkshire County and the western portions of Hampshire and Franklin Counties. The town is patrolled by the Second (Shelburne Falls) Station of Troop "B" of the Massachusetts State Police.
On the national level, Charlemont 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, Greenfield Community College, is located in Greenfield. The nearest state college is Massachusetts College of Liberal Arts in North Adams, and the nearest state university is the University of Massachusetts Amherst. The nearest private college is Williams College in Williamstown, with several others located southeast in the Northampton area.