Cumberland is known as "The Island City" because it is nearly surrounded by the waters of Beaver Dam Lake.
Cumberland is known for hosting the "Rutabaga Festival" each year, always the weekend preceding Labor Day weekend. This popular festival features live music, carnival rides, food, a parade, and a variety of other events.
According to the United States Census Bureau, the city has a total area of 4.0 square miles (10.3 km²), of which, 3.4 square miles (8.8 km²) of it is land and 0.6 square miles (1.5 km²) of it (14.82%) is water.
There were 1,013 households out of which 26.4% had children under the age of 18 living with them, 44.7% were married couples living together, 11.7% had a female householder with no husband present, and 40.0% were non-families. 35.1% of all households were made up of individuals and 19.6% had someone living alone who was 65 years of age or older. The average household size was 2.18 and the average family size was 2.79.
In the city the population was spread out with 22.5% under the age of 18, 7.3% from 18 to 24, 23.0% from 25 to 44, 22.9% from 45 to 64, and 24.3% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 89.8 males. For every 100 females age 18 and over, there were 82.2 males.
The median income for a household in the city was $32,661, and the median income for a family was $41,612. Males had a median income of $34,519 versus $21,304 for females. The per capita income for the city was $18,688. About 9.5% of families and 11.7% of the population were below the poverty line, including 18.6% of those under age 18 and 8.3% of those age 65 or over.