Millville is an unincorporated town and former city in Clayton County, Iowa, United States.

In mid 2014, the city of Millville disincorporated due to a population decrease.

According to the 2010 census, the city had a total area of 0.067 square miles (0.17 km2), all land.

[6] As of the census[1] of 2010, there were 30 people, 12 households, and 9 families living in the city.

There were 12 housing units at an average density of 171.4 per square mile (66.2/km2).

As of the census[8] of 2000, there were 23 people, 10 households, and 8 families living in the city.

20.0% of all households were made up of individuals, and none had someone living alone who was 65 years of age or older.