| State | Name | Access | Sponsored by |
| Alabama | Encyclopedia of Alabama | freely accessible | Alabama Humanities Foundation |
| Arkansas | Encyclopedia of Arkansas | freely accessible | Central Arkansas Library System |
| Colorado | Colorado Encyclopedia | freely accessible | History Colorado |
| Connecticut | Encyclopedia of Connecticut Biography (10 vols, 1917–23) | freely accessible |
| Florida | Floripedia: A Florida Encyclopedia (a collection of links to original sources, not an encyclopedia) | freely accessible | Florida Center for Instructional Technology, University of South Florida |
| Georgia | New Georgia Encyclopedia | freely accessible | Georgia Humanities and the University of Georgia Press |
| Illinois | Encyclopedia of Chicago | freely accessible | Chicago History Museum |
| Indiana | Encyclopedia of Indianapolis | freely accessible | Indianapolis Public Library |
| Kansas | Kansapedia (not to be confused with KansasPedia.com) | freely accessible | Kansas Historical Society (a state agency) |
| Kentucky | The Kentucky Encyclopedia, cached | freely accessible | University Press of Kentucky |
| Kentucky | Encyclopedia of Louisville | freely accessible | University Press of Kentucky |
| Louisiana | 64 Parishes (formerly Know Louisiana) | freely accessible | Louisiana Endowment for the Humanities |
| Maine | Maine: An Encyclopedia (cached) | freely accessible | Publius Research |
| Massachusetts | Encyclopedia of Massachusetts, biographical—genealogical (1916) | freely accessible |
| Minnesota | MNopedia | freely accessible | Minnesota Historical Society |
| Mississippi | Mississippi Encyclopedia | freely accessible | Mississippi Humanities Council
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| Missouri | Missouri Encyclopedia | freely accessible | State Historical Society of Missouri |
| Nevada | Online Nevada Encyclopedia | freely accessible | Nevada Humanities |
| New York | Encyclopedia of New York State | requires paid subscription | Available through Gale. |
| North Carolina | NCPedia | freely accessible | State Library of North Carolina |
| Ohio | Ohio History Central (archived location) | freely accessible | Ohio History Connection |
| Oklahoma | The Encyclopedia of Oklahoma History and Culture | freely accessible | Oklahoma Historical Society |
| Oregon | The Oregon Encyclopedia | freely accessible | Portland State University and the Oregon Historical Society |
| Pennsylvania | Encyclopedia of Greater Philadelphia | freely accessible | Mid-Atlantic Regional Center for the Humanities |
| South Carolina | South Carolina Encyclopedia | freely accessible | "A joint project of South Carolina Humanities, the University of South Carolina Press, the USC Libraries, the USC Center for Digital Humanities, the USC College of Arts & Sciences, the USC Institute for Southern Studies, the South Carolina State Library, and many other organizations." |
| Tennessee | Tennessee Encyclopedia | freely accessible | Tennessee Historical Society – University of Tennessee Press |
| Texas | Handbook of Texas | freely accessible | Texas State Historical Association |
| Virginia | Encyclopedia Virginia | freely accessible | Virginia Foundation for the Humanities and Library of Virginia (formerly the Virginia State Library) |
| Virginia | Encyclopedia of Virginia Biography (1915) | freely accessible | Arranged by time period and office held, not alphabetically. |
| Washington | HistoryLink | freely accessible | HistoryLink, 4Culture, King County, Washington, Seattle Office of Arts & Culture, The Norcliffe Foundation |
| West Virginia | e-WV: The West Virginia Encyclopedia | freely accessible | West Virginia Humanities Council |
| Wyoming | Encyclopedia of Wyoming | freely accessible | Wyoming State Historical Society |
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