Armstrong is a city in Emmet County, Iowa, United States. The population was 979 at the 2000 census. It was originally known as Armstrong Grove.
Armstrong is located at 43°23′45″N 94°28′51″W / 43.39583°N 94.48083°W / 43.39583; -94.48083 (43.395722, -94.480750).
According to the United States Census Bureau, the city has a total area of 0.8 square miles (2.1 km²), all of it land.