Marion was first settled in 1679 as “Sippican”, a district of Rochester, Massachusetts. The name, which also lends itself to the river which passes through the north of town and the harbor at the heart of town, was the Wampanoag name for the local tribe. The town was mostly known for its many local sea captains and sailors whose homes were in town, although there were also some small shipbuilding operations on the harbor as well. By the late 1840s, however, tensions between the village of Mattapoisett and the town led to a battle which sought to redraw the town lines and effectively take over Sippican Village.^{[citation needed]} This caused the villagers to form a committee, which went to Boston to petition for incorporation as its own town. Thus, with the help of a powerful local ally, the town was incorporated on May 14, 1852, and renamed Marion in honor of Revolutionary War hero Francis Marion. Mattapoisett was incorporated in 1857.

Since that time, Marion’s economy has mostly relied on the waters of Buzzards Bay, both for fishing and for the summer tourism industry. Recreational sailing is a major seasonal activity for residents and visitors.

According to the United States Census Bureau, the town has a total area of 26.1 square miles (67.7 km²), of which 14.0 square miles (36.2 km²) is land and 12.1 square miles (31.4 km²), or 46.46%, is water. The town is bordered by Mattapoisett to the southwest, Rochester to the northwest, and Wareham to the north and northeast. The town is approximately 15 miles (24 km) by road west of the Cape Cod Canal, 12 miles (19 km) east of New Bedford, 40 miles (64 km) east-southeast of Providence, Rhode Island, and 50 miles (80 km) south of Boston.

Marion is located on Buzzards Bay, and its geography is shaped by the water. Much of the town is separated into two halves by Sippican Harbor, with Converse Point to the west and Sippican Neck to the east. To the west of Converse Point is Aucoot Cove, where Aucoot Creek and Borden’s Brook empty into the bay. Sprague’s Cove, Hammetts Cove (which is directly east of Little Neck), Blankenship Cove and Planting Island Cove are all coves off of Sippican Harbor. To the east of Sippican Neck is Wings Cove, which separates the neck from Great Hill Point. Along the northeastern border of town is the Weweantic River, which separates the town from Wareham. The Sippican River is also a tributary to this river, and further divides the town from Wareham. Between Sippican Harbor and the Weweantic River lies the Great Swamp. To the North of Marion lies Rochester, Massachusetts. Marion has several parks, as well as wharves, beaches, The Beverly Yacht Club, Little Marion G.C. (public), and The Kittansett Club G.C. (private). Marion is a typical old New England town that has a small quaint village with many traditional Cape Cod style homes. The village includes The Marion General Store that dates back to the 1800s.

As of the census of 2000, there were 5,123 people, 1,996 households, and 1,441 families residing in the town. The population density was 350.2 people per square mile (135.2/km²). There were 2,439 housing units at an average density of 166.7 per square mile (64.4/km²). The racial makeup of the town was 92.17% White, 1.58% African American, 0.10% Native American, 0.35% Asian, 0.08% Pacific Islander, 3.46% from other races, and 2.26% from two or more races. Hispanic or Latino of any race were 0.55% of the population.

There were 1,996 households, out of which 31.7% had children under the age of 18 living with them, 61.4% were married couples living together, 8.4% had a female householder with no husband present, and 27.8% were non-families. 24.1% of all households were made up of individuals, and 11.9% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 3.00.

In the town, the population was spread out, with 25.1% under the age of 18, 4.2% from 18 to 24, 24.7% from 25 to 44, 28.3% from 45 to 64, and 17.7% who were 65 years of age or older. The median age was 42 years. For every 100 females, there were 92.4 males. For every 100 females age 18 and over, there were 87.8 males.

The median income for a household in the town was $71,250, and the median income for a family was $104,265. Males had a median income of $46,711 versus $35,911 for females. The per capita income for the town was $47,265. About 3.5% of families and 4.6% of the population were below the poverty line, including 7.0% of those under age 18 and 2.0% of those age 65 or over.

Marion is represented in the Massachusetts House of Representatives as a part of the Tenth Bristol district, which also includes Fairhaven, Mattapoisett, Rochester and a portion of Middleborough. The town is represented in the Massachusetts Senate as a part of the First Plymouth and Bristol district, which also includes Berkley, Bridgewater, Carver, Dighton, Middleborough, Raynham, Taunton, and Wareham. The town is patrolled by the Marion Police Department.

On the national level, Marion is a part of Massachusetts’s 9th congressional district, and is currently represented by William R. Keating. The state’s senior member of the United States Senate is Elizabeth Warren. The junior senator is Ed Markey.

Marion uses the open town meeting form of government, which is led by a board of selectmen. The town’s police, as well as the post office, are all located in the town’s central village. The village is also the site of the Elizabeth Taber Library, which is a member of the SAILS Library Network. The Fire/EMS Department is almost completely on-call with only (2) full-time or career members. Fire stations are located at Station No. 1 in the central village on Spring Street and Station No. 2 in East Marion at the corner of Point and Creek Rd. near the Great Swamp.