Much of the town's acreage is dominated by Totoket Mountain, part of the Metacomet Ridge, a mountainous traprock ridgeline that stretches from Long Island Sound almost to the Vermont border. The north side of Saltonstall Mountain is also located in North Branford. Totoket Mountain contains Lake Gaillard, a reservoir managed by the South Central Connecticut Regional Water Authority (SCCRWA). The SCCRWA maintains a network of hiking trails on Totoket Mountain in the Big Gulph area of Northford.
There were 5,132 households, of which 35.4% had children under the age of 18 living with them, 64.2% were married couples living together, 8.0% had a female householder with no husband present, and 24.6% were nonfamilies. 20.5% of all households were made up of individuals, and 10.2% had someone living alone who was 65 years of age or older. The average household size was 2.70, and the average family size was 3.15.
In the town, the population was spread out, with 25.6% under the age of 18, 5.7% from 18 to 24, 29.5% from 25 to 44, 25.5% from 45 to 64, and 13.7% who were 65 years of age or older; the median age was 39 years. For every 100 females, there were 94.2 males; for every 100 females age 18 and over, there were 90.9 males.
The median income for a household in the town was $64,438, and the median income for a family was $71,813. Males had a median income of $46,852 versus $33,469 for females. The per capita income for the town was $28,542. About 1.2% of families and 1.6% of the population were below the poverty line, including 0.9% of those under age 18 and 3.7% of those age 65 or over.
The High School in town is North Branford High School; they are known as the North Branford Thunderbirds.