Winthrop is a city in Buchanan County, Iowa, United States.

[6] According to the United States Census Bureau, the city has a total area of 0.84 square miles (2.18 km2), all land.

As of the census of 2020,[9] there were 823 people, 329 households, and 237 families residing in the city.

There were 344 housing units at an average density of 435.0 per square mile (168.0/km2).

As of the census[10] of 2010, there were 850 people, 346 households, and 228 families living in the city.

There were 357 housing units at an average density of 425.0 per square mile (164.1/km2).

28.9% of all households were made up of individuals, and 14.5% had someone living alone who was 65 years of age or older.

There were 341 housing units at an average density of 587.9 per square mile (227.0/km2).

33.9% of all households were made up of individuals, and 17.7% had someone living alone who was 65 years of age or older.