Directories of heads of households have been published for major cities in Iowa. The Family History Library has microfilm copies of Des Moines City direcotries for:
1866 to 1901 (FHL films 1,376,808-817)
1942, 1960, 1965, etc. (FHL book 977.758 E4pd)
Some statewide directories also list names. An example is Farmers of Iowa: A List of Farmers of Each County with Postoffice (n.p.:1892; FHL film 1,024,846)
The seven metropolitan areas of Iowa published name directories in 1856. An index to them is Elsie L. Sopp, Personal Name Index to the 1856 City Directories of Iowa (Detroit: Gale Research Co., 1980; FHL book 977.7 D42s).