Iowa has many Century Club companies - probably more than I have identified. Below are the ones I have in my data base, only two of which are public; over 30 are generational family firms. If you know of an Iowa-based business that has been in continuous, independent operation for 100 years or more, please let me know by posting a comment.
1852: Breitbach's Country Dining, Balltown 6th generation (restaurant)
1854: Hands Jewelers, Iowa City 4th generation (retail jeweler)
1854: Saboe Jewelry, West Union 2nd generation (retail jeweler)
1855: Morrison Brothers Company, Dubuque 3rd generation (manufacturing equipment)
1856: AY McDonald Manufacturing, Dubuque 5th generation (manufacturing medal products)
1856: Hubbell Realty, Des Moines 5th generation (construction & development)
1856: Laufersweiler-Sievers Funeral Home, Fort Dodge 5th generation (funeral services)
1866: Kurtz Hardware, Des Moines 5th generation (wholesale hardware)
1870: Klauer Manufacturing, Dubuque 5th generation (metal building products)
1870: Molo Companies, Dubuque 4th generation (petroleum/HVAC products & services)
1872: Chesterman Company, Sioux City 5th generation (beverage bottler & distribution)
1872: Russell Abstract & Title, Adel 5th generation
1872: Von Maur, Davenport 4th generation (department store)
1876: Decorah Greenhouses, Decorah private (retail florist)
1876: Lenz Monuments, Dubuque private (stone memorial products)
1877: Mechanical Air Systems, Mason City private (HVAC/plumbing contractor)
1878: Home Mutual Insurance Association of Carroll County, Manning mutual (insurance carrier)
1883: The Adams Company, Dubuque private (manufacturing metal parts)
1884: ALMACO, Nevada 5th generation (manufacture machinery)
1887: Cottingham & Butler, Dubuque 3rd & 4th generations (insurance broker)
1890: EJ Voggenthaler, Dubuque 4th generation (steel building materials)
1890: Engquist Lumber, Harcourt 4th generation (lumber & building materials)
1890: Marshalltown, Marshalltown private (manufacturing tools)
1891: H.L. Munn Lumber, Ames 5th generation (lumber & building materials)
1892: Geisler Brothers Company, Dubuque 5th generation (HVAC services)
1892: Seiffert Building Supplies, Davenport 2nd generation (lumber & building materials)
1893: Abeln Abstract & Title Company, Dubuque 2nd generation (real estate services)
1893: Mulgrew/Perfection Oil, Tamarack Park 4th generation? (petroleum products)
1893: West Bancorp, West Des Moines public (banking & financial services)
1894: Union-Hoeman Press, Dubuque 3rd generation (commercial printing)
1897: Kintzinger Harmon Konrady, Des Moines private (law firm)
1898: FEH Design, Des Moines private (architects)
1903: Conlon Construction, Dubuque 4th generation (construction)
1903: Lisle Corporation, Clarinda 3rd, 4th, 5th & 6th generations (manufacturing tools)
1904: Hartig Drug, Dubuque 4th generation (retail drugstore)
1904: Spahn & Rose Lumber, Dubuque 4th generation (lumber & building materials)
1905: Atlantic Bottling, Clarinda 3rd generation (beverage bottling & distribution)
1905: Farmers Lumber, Rock Valley co-op (lumber & building materials)
1907: Smith Funeral Homes and Cremation Service, Grinnell 5th generation (funeral services)
1909: Bauman's, Mount Vernon private (retail apparel)
1910: Fidelity Bank & Trust, Dyersville private (banking & financial services)
1910: Remsen Farmers Cooperative, Remsen co-op (agricultural services)
1911: Employers Mutual Casualty, Des Moines public (insurance carrier)
1914: American Pop Corn (Jolly Time), Sioux City 4th generation (popcorn & snacks)
1916: Lime Rock Springs/Pepsi-Cola Bottling Company of Dubuque, Dubuque 4th generation (beverage bottling & distribution)
1917: G&L Clothing, Des Moines private (retail apparel)
1920: O'Conner, Brooks & Co., Dubuque private (CPA/accounting services)
1920: Two Rivers Cooperative, Pella co-op (agricultural services)
1920s: Carter Printing, Des Moines 4th generation? (printing & publishing)
1924: Joetown Garage, Kalona private
[1925: Pella Corporation, Pella 3rd generation? (building products)]
Learn more about how these companies managed to thrive for a century and more in my book Lessons From Century Club Companies: Managing for Long-Term Success available in paperback and as an eBook from Amazon and Barnes & Noble