Walnut is a city in Pottawattamie County, Iowa, United States.

In recent years Walnut has become a regional center of wind turbine electrical generation.

[4] According to the United States Census Bureau, the city has a total area of 2.15 square miles (5.57 km2), all land.

There were 344 housing units at an average density of 156.5 per square mile (60.4/km2).

There were 411 housing units at an average density of 191.2 per square mile (73.8/km2).

34.7% of all households were made up of individuals, and 21.2% had someone living alone who was 65 years of age or older.

The racial makeup of the city was 97.56% White, 0.51% African American, 0.39% Asian, and 1.54% from two or more races.

27.3% of all households were made up of individuals, and 15.3% had someone living alone who was 65 years of age or older.

[12] In the 1950s the Walnut School building received an addition on its north side.

[12] By 2016 the Walnut school closed, and the four of five city council members voted to have the city buy the school, with one council member voting against.