According to the United States Census Bureau, the Yarmouth Port CDP has a total area of 6.47 square miles (16.76 km2), of which 6.04 square miles (15.65 km2) is land, and 0.43 square miles (1.11 km2) (6.86%) is water.[2]
At the 2000 census there were 5,395 people, 2,546 households, and 1,642 families in the CDP. The population density was 344.9/km2 (892.7/mi2). There were 3,104 housing units at an average density of 198.4/km2 (513.6/mi2). The racial makeup of the CDP was 98.46% White, 0.26% African American, 0.17% Native American, 0.32% Asian, 0.02% Pacific Islander, 0.19% from other races, and 0.59% from two or more races. Hispanic or Latino people of any race were 0.70%.[5]
Of the 2,546 households 17.0% had children under the age of 18 living with them, 56.2% were married couples living together, 6.8% had a female householder with no husband present, and 35.5% were non-families. 30.8% of households were one person and 19.8% were one person aged 65 or older. The average household size was 2.11 and the average family size was 2.61.
The age distribution was 15.8% under the age of 18, 3.0% from 18 to 24, 18.7% from 25 to 44, 27.9% from 45 to 64, and 34.7% 65 or older. The median age was 53 years. For every 100 females, there were 85.9 males. For every 100 females age 18 and over, there were 80.7 males.
The median household income was $47,576 and the median family income was $57,841. Males had a median income of $41,029 versus $30,171 for females. The per capita income for the CDP was $30,418. About 2.2% of families and 4.3% of the population were below the poverty line, including 6.2% of those under age 18 and 1.3% of those age 65 or over.