Calumet is a city in Itasca County, Minnesota, United States. The population was 334 at the 2020 census. A post office called Calumet …Calumet is a city in Itasca County, Minnesota, United States. The population was 334 at the 2020 census. A post office called Calumet has been in operation since 1908. The city was named after the French, colonial-era word often used for a Native American ceremonial pipe.