Plymouth County Historical Museum is located in Le Mars, Iowa, United States.

The two-story, brick, Colonial Revival structure was designed by the Chicago architectural firm of Atchison and Edbrooke.

Sympathetic in style to the original building, the addition was designed by Beuttler & Arnold of Sioux City, and constructed by Devereux and Olsen of Minneapolis.

The Plymouth County Historical Society occupies the 1924 addition, and utilizes the space for their local history museum.

This article about a property in Plymouth County, Iowa on the National Register of Historic Places is a stub.