Calumet City is a city in Cook County, Illinois, United States. The population was 39,072 at the 2000 census. The ZIP code is 60409. Calumet City (commonly referred to locally as "Cal City") was founded in 1892 when the villages of Schrumville and Sobieski Park merged under the name of West Hammond, since it lies on the west side of the Illinois-Indiana border from Hammond, Indiana. In 1924, West Hammond officially changed its name to Calumet City. In addition to being bordered to the east by Hammond, it is also bordered by Burnham and Chicago to the north, Lansing to the south, and South Holland and Dolton to the west.