Each state has its own Historical Marker Program. They decide which historical places should be marked. The roadside signs are funded by taxpayer dollars.

Google "Sarah Estell" - there is a picture of a historical marker that has information about her. She was a free black woman in the slavery era.

http://www.hmdb.org/marker.asp?marker=28465

Squanto, as a significant historical figure who played a crucial role in relations between the Native Americans and Pilgrims, could be considered for a grave marker to honor his legacy and contributions. A marker could serve as a symbol of remembrance and recognition for his impact on early American history.