Idaho is rewriting its highway historical markers sign by sign: the Idaho Transportation Department and the Idaho State Historical Society are replacing every marker text with new signs, district by district, through 2027. The new signs already standing, thirty-nine across the Panhandle as of September 2026, now have permanent pages at TreeAlive, each carrying the program's current text on georeferenced maps from the eras it describes and pinned where the Department's own inventory places the sign. Older texts on signs not yet replaced are not shown.
39Marker pages
82,000+Historical map sheets
Idaho Transportation Department (ITD) in partnership with the Idaho State Historical Society (ISHS)Credited on every page
Every dot is a live page. Click one to preview it or add it to a road trip; many dots hold several markers each; click a busy spot to zoom in. Prefer a list? Browse all 39 markers by county.
TreeAlive maps family trees. When a visitor's ancestors lived in Idaho, the markers standing near those places surface automatically alongside their family's journey:
The Big Blowup · near where a family lived in the Silver Valley in 1910 · devastating fires swept through here in 1910, culminating in August’s Big Blowup
When a marker stands near a place in your own tree, you have a personal reason to go see it. Open the live demo tree, choose the Crossings tab, and turn on Historical Markers to see the experience working (the demo family’s markers are in Pennsylvania; an Idaho family sees Idaho’s).
Browsing all 39 markers by county.
Scan: the Big Blowup marker page