Illinois - Criteria: A (event)
| Hotel Roodhouse |
| Hotel Stratford |
| Hotel Waukegan |
| Hotel Windermere East |
| House at 380 Chiltern Drive-Deerpath Hill Estates |
| House at 965 Castlegate Court-Deerpath Hill Estates |
| Humboldt Park |
| Hunt House |
| Hyde Park-Kenwood Historic District |
| Iles, Elijah, House |
| Illinois and Michigan Canal |
| Illinois Central Railroad and Toledo, Peoria, and Western Railroad Freight House |
| Illinois Central Railroad Depot |
| Illinois Central Railroad Depot |
| Illinois Central Railroad Depot |
| Illinois Central Railroad Passenger Depot |
| Illinois Central Railroad Water Tower and Pump House |
| Illinois Central Stone Arch Railroad Bridges |
| Illinois Department of Mines and Minerals-Springfield Mine Rescue Station |
| Illinois Industrial School for Girls |
| Illinois Institute of Technology Academic Campus |
| Illinois Iron Furnace |
| Illinois National Guard Armory |
| Illinois State Bank Building |
| Illinois State Fairgrounds |
| Illinois State Police Office, Pontiac |
| Illinois Traction Building |
| Illinois Traction System Mackinaw Depot |
| Illinois Waterway Project Office |
| Independence Park |
| Indian Boundary Park |
| Indian Ford Bridge |
| Inland Steel Building |
| Inman Hotel |
| International Harvester Building |
| International Tailoring Company Building |
| Jackson County Courthouse |
| Jacksonville Downtown Historic District |
| Jacksonville Historic District |
| Jacksonville Labor Temple |
| Jacksonville Public Library |
| Jefferson Park |
| Jennings Ford Automobile Dealership |
| Jensen, Chris, Round Barn |
| Jersey County Courthouse |
| Jerseyville Downtown Historic District |
| Jewish People's Institute |
| Johnson County Courthouse |
| Joliet East Side Historic District |
| Joliet, Louis, Hotel |
| Joliet Municipal Airport |
| Joliet Steel Works |
| Jubilee College |
| Judson, The |
| Kamp Store |
| Kankakee County Courthouse |
| Kappa Delta Rho Fraternity House |
| Kappa Kappa Gamma Sorority House |
| Kappa Sigma Fraternity House |
| Keithsburg Historic District |
| Kellogg's Grove |
| Kendall County Courthouse |
| Kewanee Hotel |
| Kewanee Public Library |
| Kimball, William W., House |
| King, Moses, Brick and Tile Works |
| Kitchell Park |
| Kleinkopf, Clarence, Round Barn |
| Knobeloch-Seibert Farm |
| Knox County Courthouse and Hall of Records |
| Knox County Jail |
| Koster Site |
| La Grange Lock and Dam Historic District |
| LaHarpe City Hall |
| LaHarpe Historic District |
| Lake Bluff Uptown Commercial Historic District |
| Lake Ellyn Park |
| Lake Forest Historic District |
| Lake Shore Apartments |
| Lakeside Press Building |
| Lakewood Balmoral Historic District |
| Lamoine Hotel |
| Larkin Home for Children |
| LaSalle City Building |
| LaSalle Downtown Commercial District |
| LaSalle Street Auto Row Historic District |
| Lathrop, Julia C., Homes |
| Lawrence County Courthouse |
| Lawson, Victor F., House YMCA |
| Lazy A Motel |
| Lebanon Historic District |
| LeClaire Historic District |
| LeClaire Hotel |
| Legler, Henry E., Regional Branch of the Chicago Public Library |
| Lemont Downtown Historic District |
| Lemont Methodist Episcopal Church |
| Lena Water Tower |
| LeRoy Commercial Historic District |
| Liberty Theater |
| Libertyville High School Brainerd Building |
Data from United States Park Service and Wikidata
