Hiawatha is named after a poem by Henry Wadsworth Longfellow called The Song of Hiawatha. In the poem is legendary Onondaga and Mohawk Indian leader Hiawatha. Adjacent to the former Ioway-Sac reservation and the present-day Ioway Tribe of Kansas and Nebraska, Hiawatha is called Hári Wáta in Ioway, meaning "I am looking far away". This name may be the result of choosing Ioway words that sound like the English name. It has nothing to do with the Onondaga-Mohawk leader.
Hiawatha is nicknamed the "City of Beautiful Maples" because of its countless trees that produce delightful colors in the fall season. The city also has the oldest Halloween parade in the nation, starting in 1914. The year 2007 marked Hiawatha's 150th anniversary.
Hiawatha's population was estimated to be 3,237 in the year 2006, a decrease of 180, or -5.3%, over the previous six years.
As of the census of 2000, there were 3,417 people, 1,466 households, and 914 families residing in the city. The population density was 1,529.2 people per square mile (591.6/km²). There were 1,646 housing units at an average density of 736.7/sq mi (285.0/km²). The racial makeup of the city was 91.43% White, 2.78% African American, 2.19% Native American, 0.15% Asian, 1.20% from other races, and 2.25% from two or more races. Hispanic or Latino of any race were 2.99% of the population.
There were 1,466 households out of which 28.4% had children under the age of 18 living with them, 50.2% were married couples living together, 9.8% had a female householder with no husband present, and 37.6% were non-families. 34.0% of all households were made up of individuals and 19.0% 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 2.91.
In the city the population was spread out with 24.4% under the age of 18, 7.7% from 18 to 24, 23.8% from 25 to 44, 21.9% from 45 to 64, and 22.1% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 87.4 males. For every 100 females age 18 and over, there were 82.6 males.
The median income for a household in the city was $35,854, and the median income for a family was $46,310. Males had a median income of $31,843 versus $20,385 for females. The per capita income for the city was $16,981. About 8.5% of families and 9.0% of the population were below the poverty line, including 11.3% of those under age 18 and 6.8% of those age 65 or over.