[3][4] It is the largest town on the Iowa side of the Missouri River between Council Bluffs and Sioux City.

Onawa was named for a character mentioned in the poem The Song of Hiawatha by Henry Wadsworth Longfellow.

[6] The city is known for having the widest main street in the continental United States.

[7] Onawa was the site of a prisoner-of-war (POW) camp for captured German soldiers between 1944 and 1946.

A larger camp existed near the central Iowa town of Algona, and housed as many as 5,400 German POWs.

[9] According to the United States Census Bureau, the city has a total area of 5.19 square miles (13.44 km2), all land.

[10] Onawa is located in the Loess Hills region of western Iowa, a unique geological and environmental area.

Thirty-eight point nine percent of all households were made up of individuals, and 20.9% had someone living alone who was 65 years of age or older.

35.0% of all households were made up of individuals, and 20.2% had someone living alone who was 65 years of age or older.

[14] The Eskimo Pie was created in Onawa in 1920 by Chris Nelson, an ice cream shop owner.