According to the United States Census Bureau, the town has a total area of , of which, of it is land and of it (12.35%) is water.
There are four distinct season in Essex. During Autumn, the leaves change colors and the temperatures fall. The average November high temperature is about 50 degrees. Snow is prevalent in winter, typically starting in December and lasting through March. The average January low temperature is about 19 degrees. In recent years winter have become erratic, with the first snowfall of winter 2006-2007 not reported until mid-late January. However, the winter of 2008-2009 was unusually cold and snowy, with over 50 inches of snow (compared to an average of about 30 inches) and days with temperatures below 0 degrees Fahrenheit in the morning. Spring is pleasant with temperatures averaging in the 60s. Summertime in Essex is warm and humid, with average July temperatures into the 80s.
As of the census of 2000, there were 6,505 people, 2,811 households, and 1,776 families residing in the town. The population density was 627.6 people per square mile (242.4/km²). There were 2,977 housing units at an average density of 287.2 per square mile (110.9/km²). There were 2,811 households out of which 27.2% had children under the age of 18 living with them, 55.6% were married couples living together, 5.2% had a female householder with no husband present, and 36.8% were non-families. 31.8% of all households were made up of individuals and 16.3% had someone living alone who was 65 years of age or older. The average household size was 2.27 and the average family size was 2.87.
In the town the population was spread out with 21.9% under the age of 18, 3.6% from 18 to 24, 27.4% from 25 to 44, 27.7% from 45 to 64, and 19.5% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 89.6 males. For every 100 females age 18 and over, there were 86.9 males.
The median income for a household in the town was $66,746, and the median income for a family was $88,888. Males had a median income of $54,053 versus $38,276 for females. The per capita income for the town was $42,806. About 0.5% of families and 2.8% of the population were below the poverty line, including 1.0% of those under age 18 and 3.5% of those age 65 or over.
The Great Attack