Atkinson's history dates back to the American Revolution. The community was incorporated 3 September 1767, and was named after Colonel Theodore Atkinson, a local landowner. Atkinson Academy, the second-oldest co-educational school in the country, was founded as a boys' school in 1787 by Reverend Stephen Peabody, General Nathaniel Peabody and Doctor William Cogswell; it began admitting girls in 1791. The school building burnt to the ground in 1802, and was rebuilt in 1803 at a cost of $2,500. That building remains a part of the Academy, which has since been expanded, with only four classrooms. Other historic buildings include the Atkinson Historical Society, the Kimball Public Library, and the Rockwell School. Atkinson's history can be read about in the book Atkinson Then and Now, which can be purchased at the Atkinson Public Library on Academy Avenue. Atkinson celebrated its 250-year anniversary Labor Day weekend 2017.
As of the census of 2000, there were 6,178 people, 2,317 households, and 1,777 families residing in the town. The population density was 555.2 people per square mile. There were 2,431 housing units at an average density of 218.5 per square mile. The racial makeup of the town was 97.62% White, 0.26% African American, 0.06% Native American, 1.18% Asian, 0.21% from other races, and 0.66% from two or more races. Hispanic or Latino of any race were 0.70% of the population. There were 2,317 households, out of which 32.5% had children under the age of 18 living with them, 68.8% were married couples living together, 5.7% had a female householder with no husband present, and 23.3% were non-families. 19.0% 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 2.66 and the average family size was 3.08. In the town, the population was spread out, with 24.5% under the age of 18, 5.0% from 18 to 24, 28.4% from 25 to 44, 30.7% from 45 to 64, and 11.4% who were 65 years of age or older. The median age was 41 years. For every 100 females, there were 94.9 males. For every 100 females age 18 and over, there were 96.1 males. The median income for a household in the town was $69,729, and the median income for a family was $77,631. Males had a median income of $53,229 versus $34,760 for females. The per capita income for the town was $30,412. About 2.3% of families and 3.3% of the population were below the poverty line, including 4.5% of those under age 18 and 2.2% of those age 65 or over.
