Walnut is a city in Pottawattamie County, Iowa, United States. The population was 778 at the 2000 census. Walnut is located on Interstate 80 and is famous for its many antique stores. In recent years Walnut has become a regional center of wind turbine electrical generation.
Walnut is located at 41°28′52″N 95°13′16″W / 41.48111°N 95.22111°W / 41.48111; -95.22111 (41.480999, -95.221116).
According to the United States Census Bureau, the city has a total area of 2.1 square miles (5.5 km²), all of it land.