2010 census

As of the census^[16] of 2010, there were 7,437 people, 2,826 households, and 2,155 families living in the city. The population density was 465.4 inhabitants per square mile (179.7/km²). There were 3,209 housing units at an average density of 200.8 per square mile (77.5/km²). The racial makeup of the city was 96.5% White, 0.4% African American, 0.2% Native American, 1.1% Asian, 0.6% from other races, and 1.1% from two or more races. Hispanic or Latino of any race were 1.7% of the population.

There were 2,826 households, of which 35.2% had children under the age of 18 living with them, 67.7% were married couples living together, 5.5% had a female householder with no husband present, 3.1% had a male householder with no wife present, and 23.7% were non-families. 18.5% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.02. As of the 2013 American Community Survey, the Orono median household and family incomes are $100,362 and $117,024, respectively. Less than 2.5% of all families are living at or below the poverty level.^[17]

The median age in the city was 45.7 years. 26.6% of residents were under the age of 18; 4.3% were between the ages of 18 and 24; 17.7% were from 25 to 44; 38.8% were from 45 to 64; and 12.6% were 65 years of age or older. The gender makeup of the city was 51.2% male and 48.8% female.

2000 census

As of the census^[4] of 2000, there were 7,538 people, 2,766 households, and 2,196 families living in the city. The population density was 468.9 inhabitants per square mile (181.0/km²). There were 2,909 housing units at an average density of 181.0 per square mile (69.9/km²). The racial makeup of the city was 97.73% White, 0.27% African American, 0.15% Native American, 0.94% Asian, 0.24% from other races, and 0.68% from two or more races. Hispanic or Latino of any race were 0.86% of the population.

There were 2,766 households, out of which 38.0% had children under the age of 18 living with them, 71.8% were married couples living together, 5.2% had a female householder with no husband present, and 20.6% were non-families. 15.8% of all households were made up of individuals, and 4.2% had someone living alone who was 65 years of age or older. The average household size was 2.72 and the average family size was 3.06.

In the city, the population was spread out, with 27.4% under the age of 18, 4.5% from 18 to 24, 26.7% from 25 to 44, 32.5% from 45 to 64, and 9.0% who were 65 years of age or older. The median age was 41 years. For every 100 females, there were 103.5 males. For every 100 females age 18 and over, there were 102.0 males.

The median income for a household in the city was $88,314, and the median income for a family was $101,114. Males had a median income of $61,913 versus $34,964 for females. The per capita income for the city was $65,825. About 0.5% of families and 1.2% of the population were below the poverty line, including 1.0% of those under age 18 and 1.6% of those age 65 or over.