From 1914 to 1933, the Pennsylvania Historical Commission, predecessor to the Pennsylvania Historical and Museum Commission (PHMC), installed bronze plaques to commemorate significant individuals, events, and landmarks throughout the state. However, during the 1920s and 1930s, with accelerated automobile speeds, these plaques became impossible to read from a moving vehicle. For this reason, the PHMC, created by the state legislature in 1945, developed the modern style of historical marker.
The PHMC dedicated the first of its historical markers in September 1946 on U.S. Route 22, fourteen miles east of Harrisburg . It was titled "Hanover Resolves" and indicated the location of the earliest decree for independence in the state. Since this time, the PHMC has adopted more stringent criteria for approval of state historical markers.
The guidelines formulated in the late 1970s require "that the person, event or site to be commemorated have had a meaningful impact on its times and be of statewide or national rather than only local significance." In June 2008, with the most recent revision of the program’s guidelines, the agency adopted a standard that requires that “the nomination is clear and organized and includes thorough documentation (with selected photocopies and bibliographies from primary and secondary sources) and verification of the facts claimed.” Additionally, a person being nominated must have been deceased for at least ten years.
Pennsylvania's State Historical Marker Program, in its second half-century, continues to study technological changes and evolving concepts of safety, accessibility, and readability. More importantly, however, the program is endeavoring to meet its obligation to interpret ever more fully and fairly the great spectrum of Pennsylvania's history.