Canals and Rivers
- Chesapeake and Ohio Canal
- Erie Canal
- Ohio and Erie Canal
- Susquehanna and Tidewater Canal
- The Miami & Erie Canal
- Wabash & Erie Canal
Education
Historical Societies
- Colorado: History Colorado
- Daughters of the American Revolution
- Daughters of Utah Pioneers
- E Clampus Vitus
- Florida: Sanford Historic Preservation Board
- Florida: West Volusia Historical Society
- Georgia: Georgia Historical Society/Commission
- Idaho: Idaho State Historical Society
- Illinois: Illinois State Historical Society
- Illinois: Looking for Lincoln
- Indiana: Indiana Cemetery Heritage
- Indiana: Indiana State Historical Bureau Markers
- Iowa: State Historical Society of Iowa
- Kansas: Kansas Historical Society
- Kentucky: Kentucky Historical Society
- Maryland: Washington County Historical Advisory Committee
- Massachusetts: Massachusetts Bay Colony—Tercentenary Commission Markers
- Michigan: Michigan Historical Commission
- Minnesota Historical Society
- Missouri, Historical Markers of Springfield & Greene County
- Missouri: State Historical Society of Missouri
- Native Sons/Daughters of the Golden West
- Nebraska: Nebraska State Historical Society
- New Jersey: Bergen County Historical Society
- New Jersey: Hunterdon County Cultural and Heritage Commission
- New Jersey: Morris County Heritage Commission
- New Jersey: Sussex County Board of Chosen Freeholders
- New York: Historical Society of Rockland County
- Ohio Revolutionary Memorial Commission
- Ohio: Delaware County Historical Society
- Ohio: Ohio Historical Society
- Pennsylvania: The Harrisburg History Project
- Sons of Confederate Veterans/United Confederate Veterans
- Sons of the American Revolution
- Sons of Utah Pioneers
- South Carolina: Abbeville County Historical Society/Commission
- South Carolina: Aiken County Historical Commission
- South Carolina: Aiken County Historical Society
- South Carolina: Anderson County Historical Association/Society
- South Carolina: Beaufort County Historical Society
- South Carolina: Calhoun County Historical Commission/Society
- South Carolina: Charleston County, St. James- Santee Parish Historical Society
- South Carolina: Cherokee County Historical and Preservation Society
- South Carolina: Chester County Historical Commission
- South Carolina: Chesterfield County Historical and Preservation Societies
- South Carolina: Colleton County Historical Society
- South Carolina: Greenville County Historic Preservation Commission
- South Carolina: Greenwood County Historical Society
- South Carolina: Laurens County Historical Society
- South Carolina: McCormick County Historical Commission
- South Carolina: McCormick County Historical Society
- South Carolina: Preservation Society of Charleston
- South Carolina: Saluda County Historical Commission
- South Carolina: Saluda County Historical Society
- South Carolina: Union County Historical Society
- South Carolina: Williamsburg County Historical Society
- South Carolina: Williamsburg County, Three Rivers Historical Society
- South Carolina: York County Historical Commission
- United Daughters of the Confederacy
- Utah Pioneer Trails and Landmarks Association
- Virginia: Fairfax County History Commission
- Virginia: Prince William County Historical Commission
- Wisconsin: Dane County Historical Society
- Wisconsin: Madison Landmarks Commission
- Wisconsin: Wisconsin Historical Society
International
Music
Railroads and Trains
- Baltimore and Ohio Railroad (B&O)
- Erie & Kalamazoo Railroad
- Manassas Gap Railroad
- Orange and Alexandria Railroad
- Pennsylvania Railroad
- Southern Pacific Railroad
- Transcontinental Railroad
- Washington and Old Dominion Railroad
Roads and Trails
- Antonio de Espejo Entrada of 1582-1583
- Braddock's Road and Maj. Gen. Edward Braddock
- California Trail
- Dominguez y Escalante Expedition
- El Camino Real de los Tejas National Historic Trail
- El Camino Real de Tierra Adentro
- Forbes Road
- Great Indian Warrior / Trading Path
- Harriet Tubman Underground Railroad Byway
- Juan Bautista de Anza National Historic Trail
- Juan Caspar de Portolá Expedition
- Lewis & Clark Expedition
- Lincoln Highway
- Mark Twain Bret Harte Trail
- Mormon Pioneer Trail
- Natchez Trace
- Oregon Trail
- Pony Express National Historic Trail
- Santa Fe Trail
- The Comanche Trail into Mexico
- The Historic National Road
- The Mojave Road (Old Government Road)
- The Overland Trail
- Trail of Tears
- U.S. Route 66
- William Bartram Trails
- Wisconsin: Wisconsin's Maritime Trails
Uncategorized
- American Quarter Horse Markers
- Belleville, NJ: Belleville Historical Society
- California Historical Landmark
- California Historical Landmark
- California Historical Landmark
- California Sesquicentennial Event
- California State Historic Landmark
- California State Historical Landmark
- California State Historical Landmark
- Connecticut Military Veterans
- Department of historical resources
- Duluth, Minnesota Skyline Drive Commemorative Plaques
- E Clampus Vitus
- Geological Society of Minnesota
- George Washington Slept Here
- Harriman Park, New York
- Harriman Park, New York
- Harriman Park, New York
- https://www.hmdb.org/marker.asp?marker=18168
- Liberty Bell Replica
- Markers Attached to Sculpture
- Martin Luther King, Jr.
- Minnesota CCC Projects
- Minnesota Department of Highways
- Minnesota NYA Projects
- Minnesota State Monuments
- Minnesota: Fort Ridgely Interpretive Series
- Minnesota: Scott County Historical Society
- Mississippi Freedom Trail
- Mississippi Freedom Trail
- More Than Words
- National Historic Landmarks
- New York: Historic New York
- Pacific Grove Historical Mural Projects
- Postal Mail and Philately
- Signers of the Declaration of Independence
- Spirit of the American Doughboy - E. M. Viquesney
- Statue of Liberty Replicas
- Stephen Tyng Mather
- Strange But True
- Texas 1936 Centennial Markers and Monuments
- The Industrial Heritage Trail
- The Spirit of 76, America's Bicentennial Celebration
- United Nations Educational, Scientific and Cultural Organization
- Whiskey Rebellion
- Works Progress Administration (WPA) projects
- WWII France
Walking and Driving Tours
- Arizona: Historic Florence Walking Tour
- Arizona: Pistols, Plows and Petticoats Historic Driving Tour
- Arizona: The Presidio Trail
- Blue Ridge Parkway
- California: Gaslamp Quarter - San Diego
- California: Sutter Creek Gold Mine Trail
- Florida: St. Augustine Freedom Trail
- Great Lakes Seaway Trail National Scenic Byway
- Illinois: Lincoln Home National Historic Site
- Maine: Portland Freedom Trail
- Maryland: Baltimore City Historical Markers
- Maryland: Bolton Hill Historic District
- Maryland: Chesapeake City Historic District
- Maryland: Fort McHenry
- Maryland: Gwynns Falls Trail
- Maryland: Lost Rockville – 1801 to 1850
- Maryland: Rockville's African American Heritage Walking Tour
- Maryland: Saint Mary's City
- New Jersey: Fort Hancock Walking Tour
- Pennsylvania: Battle of Hanover Walking Tour
- Pennsylvania: Seminary Ridge Historic Walking Tour
- South Carolina: Abbeville Historical Sites Tour
- South Carolina: South Carolina Heritage Corridor
- South Carolina: Spartanburg Music Trail
- Utah: Kanab, Utah "Walk of Fame"
- Utah: Salt Lake City Downtown Walking Tour
- Virginia, Wartime Manassas Walking Tour
- Virginia: City of Falls Church
- Virginia: Historic Occoquan
- Virginia: Norfolk Heritage Cannonball Trail
- Virginia: Old Town Alexandria
- Washington DC, Logan Circle Heritage Trail
- Washington, D.C.: African American Heritage Trail
War: Mexican American
War: Spanish-American War
War: US Civil War
- Antietam Campaign War Department Markers
- Battlefield Markers Association
- Battlefield Trails - Civil War
- Chickamauga Campaign Heritage Trail
- Civil War to Civil Rights
- D.S. Freeman (Richmond Battlefields)
- Defenses of Washington
- Gettysburg Campaign
- Lincoln 1861 Inaugural Train Stops
- Maryland Civil War Trails
- Missouri, Battle of Springfield
- Missouri: A State Divided: The Civil War in Missouri
- North Carolina Civil War Trails
- Ohio: Morgan's Raid - Jefferson County, Ohio
- Pennsylvania: Pennsylvania Civil War Trails
- Shermans March to the Sea
- Tennessee: Tennessee Civil War Trails
- Virginia Civil War Trails
- West Virginia Civil War Trails
War: US Indian War
War: US Revolutionary War
- Battlefield Trails - Revolutionary War
- General Henry Knox Trail
- General Herkimer's 40 Mile March
- The Sullivan Expedition Against the Iroquois Indians
- The Washington-Rochambeau Route