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

[4] Treynor began east of Council Bluffs, IA in the late 1880s with the establishment of Fritz Eyberg's General Store, August Olderog's dance hall and saloon, and St Paul's German Evangelical Church.

The vicinity east of Middle Silver Creek had previously been known for its number of wolves.

Local German immigrant farmers referred to the settlement as Four Corners or High Five, a popular card name, until the post office opened in the early 1890s as Treynor, named after the recently deceased Council Bluffs postmaster.

By the time the town was incorporated in 1905, it included two general stores, two saloons, a furniture/implement house, a livery stable, several blacksmith shops, and the Treynor State Bank.

An Air Force radar base operated just outside town during the early years of the Cold War.

According to the United States Census Bureau, the city has a total area of 0.58 square miles (1.50 km2), all land.

23.4% of all households were made up of individuals, and 10.8% had someone living alone who was 65 years of age or older.

The racial makeup of the city was 99.68% White, 0.11% African American and 0.21% Asian.

Treynor Community School District serves the town and the surrounding areas.