As of 2000, the population was 40,563. Its county seat and most populous municipality is Centreville. The census-designated place of Stevensville is the county's most populous place. Queen Anne's County is named for Queen Anne of Great Britain who reigned when the county was established in 1706.
It was the home of baseball Hall of Famer Jimmie Foxx.
There were 15,315 households out of which 33.30% had children under the age of 18 living with them, 62.20% were married couples living together, 9.50% had a female householder with no husband present, and 24.60% were non-families. 19.60% of all households were made up of individuals and 7.90% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 2.99.
In the county the population was spread out with 25.40% under the age of 18, 5.80% from 18 to 24, 30.10% from 25 to 44, 25.90% from 45 to 64, and 12.90% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 99.20 males. For every 100 females age 18 and over, there were 96.80 males.
The median income for a household in the county was $57,037, and the median income for a family was $63,713. Males had a median income of $44,644 versus $30,144 for females. The per capita income for the county was $26,364. About 4.40% of families and 6.30% of the population were below the poverty line, including 7.20% of those under age 18 and 7.30% of those age 65 or over.
All are classified as towns under Maryland law.
Unincorporated areas are also considered as towns by many people and listed in many collections of towns, but they lack local government. Various organizations, such as the United States Census Bureau, the United States Postal Service, and local chambers of commerce, define the communities they wish to recognize differently, and since they are not incorporated, their boundaries have no official status outside the organizations in question. The Census Bureau recognizes the following census-designated places in the county:
Other unincorporated places not listed as CDPs are: