Gaastra is a city in Iron County in the U.S. state of Michigan. As of the 2010 census, the city population was 347, making it Michigan's third-smallest incorporated city. The city is named after Douwe Gaastra, a building contractor and real estate speculator who bought the land in October 1908 and platted the town. It was incorporated as a village in 1919 and as a city in 1949. Bucky Holm is the current mayor of Gaastra.
According to the United States Census Bureau, the city has a total area of 1.6 square miles (4.3 km²), all land.
As of the census of 2000, there were 339 people, 146 households, and 102 families residing in the city. The population density was 205.9 per square mile (79.3/km²). There were 164 housing units at an average density of 99.6 per square mile (38.4/km²). The racial makeup of the city was 97.35% White, 0.59% Native American, 0.59% from other races, and 1.47% from two or more races. Hispanic or Latino of any race were 0.88% of the population. 22.0% were of Italian, 20.1% Polish, 13.9% Finnish, 10.6% French and 8.1% American ancestry according to Census 2000. 97.3% spoke English and 2.7% Polish as their first language.