Archaeological site, northeastern Iowa, U.S. Located on the Mississippi River, it covers 4 sq mi (10 sq km). Established in 1949, the monument has 183 known mounds, some of which are in the shape of birds and bears. The mounds were built over the course of the Woodland period (1000 BC–AD 1200), with the effigy mounds probably constructed between AD 400 and 1200. Many mounds have yielded copper, bone, and stone tools of Indian origin. One of the bear mounds is 137 ft (42 m) long and 3.5 ft (1 m) high.
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According to the United States Census Bureau, the city has a total area of 1.2 square miles (3.2 km²), all of it land.
There were 407 households out of which 36.1% had children under the age of 18 living with them, 35.1% were married couples living together, 24.6% had a female householder with no husband present, and 35.1% were non-families. 31.9% of all households were made up of individuals and 15.5% had someone living alone who was 65 years of age or older. The average household size was 2.62 and the average family size was 3.33.
In the city the population was spread out with 33.4% under the age of 18, 7.9% from 18 to 24, 22.2% from 25 to 44, 18.3% from 45 to 64, and 18.3% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 83.1 males. For every 100 females age 18 and over, there were 75.5 males.
The median income for a household in the city was $17,727, and the median income for a family was $20,125. Males had a median income of $27,500 versus $16,250 for females. The per capita income for the city was $11,035. About 38.1% of families and 42.8% of the population were below the poverty line, including 59.7% of those under age 18 and 19.6% of those age 65 or over.