According to the United States Census Bureau, the town has a total area of 56.6 square miles (147 km2), of which, 54.3 square miles (141 km2) of it is land and 2.2 square miles (5.7 km2) of it (3.96%) is water.
As of the census of 2000, there were 8,333 people, 3,174 households, and 2,285 families residing in the town. The population density was 153.4 people per square mile (59.2/km²). There were 4,015 housing units at an average density of 73.9 per square mile (28.5/km²). The racial makeup of the town was 97.26% White, 0.84% African American, 0.28% Native American, 0.40% Asian, 0.46% from other races, and 0.77% from two or more races. Hispanic or Latino of any race were 0.98% of the population.
There were 3,174 households out of which 35.2% had children under the age of 18 living with them, 62.3% were married couples living together, 6.9% had a female householder with no husband present, and 28.0% were non-families. 21.4% of all households were made up of individuals and 8.1% had someone living alone who was 65 years of age or older. The average household size was 2.58 and the average family size was 3.02.
In the town the population was spread out with 25.5% under the age of 18, 4.8% from 18 to 24, 33.3% from 25 to 44, 25.8% from 45 to 64, and 10.6% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 100.1 males. For every 100 females age 18 and over, there were 96.2 males.
The median income for a household in the town was $62,304, and the median income for a family was $70,091. Males had a median income of $45,500 versus $36,055 for females. The per capita income for the town was $28,112. About 1.0% of families and 2.9% of the population were below the poverty line, including 1.5% of those under age 18 and 1.5% of those age 65 or over.
Voter Registration and Party Enrollment as of October 25, 2005
The East Haddam Public School System has about 1,420 students in grades PreK–12; about 121 certified "teachers", 70 support staff and 8 administrators. Dr. Ellen Solek is superintendent of schools. Located in Moodus, Connecticut, the three schools in the public school system are:
Franklin Academy – "A Boarding and Day School for Students with Nonverbal Learning Differences in grades 8-12", according to the school's Web site. The private, nonprofit school was opened in 2003 and has a campus of 75 acres (300,000 m2).
East Haddam Libraries - 2 public libraries, The East Haddam Free Public Library (18 Plains Rd, Moodus) and The Rathbun Free Memorial Library (36 Main St, East Haddam). EHFPL is well known for its teen and family programs, while Rathbun Library is known for its adult and child programs. Both have special collections in addition to offering basic library fare: Books for readers of all ages, DVD/Videos, Public Computer access, etc.
East Haddam Historical Society Museum – local history exhibits, including pictures of the construction of the East Haddam swing bridge, the world's largest.