Portage was named for the Fox-Wisconsin Waterway, a portage between the Fox River and the Wisconsin River, which was recognized by Jacques Marquette and Louis Joliet during their discovery of a route to the Mississippi River in 1673. The city's slogan is "Where the North Begins".
As of the census of 2000, there were 9,728 people, 3,770 households, and 2,228 families residing in the city. The population density was 1,172.9 people per square mile (453.1/km²). There were 3,970 housing units at an average density of 478.7/sq mi (184.9/km²). The racial makeup of the city was 92.76% White, 3.90% African American, 0.51% Native American, 0.71% Asian, 0.05% Pacific Islander, 0.85% from other races, and 1.21% from two or more races. Hispanic or Latino of any race were 3.39% of the population.
There were 3,770 households out of which 30.1% had children under the age of 18 living with them, 44.5% were married couples living together, 10.7% had a female householder with no husband present, and 40.9% were non-families. 34.5% of all households were made up of individuals and 14.4% had someone living alone who was 65 years of age or older. The average household size was 2.30 and the average family size was 2.96.
In the city the population was spread out with 23.3% under the age of 18, 10.6% from 18 to 24, 31.7% from 25 to 44, 19.3% from 45 to 64, and 15.2% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 106.1 males. For every 100 females age 18 and over, there were 108.7 males.
The median income for a household in the city was $35,815, and the median income for a family was $44,804. Males had a median income of $33,158 versus $23,478 for females. The per capita income for the city was $18,039. About 4.6% of families and 7.2% of the population were below the poverty line, including 7.5% of those under age 18 and 7.8% of those age 65 or over.
Three interstate highways, Interstate 94,Interstate 90, and Interstate 39 run past Portage, giving the city a 30-minute commute to Madison and 15-minute commute to Wisconsin Dells. The city also lies only a few hours from Milwaukee, Chicago, and Minneapolis/ Saint Paul, MN.