We all believe what signs tell us and rightfully so, BUT sometimes historical signs make mistakes, or the sign erectors NOT doing the research they should. Locally the worst example is the John Morton Homestead in Prospect Park now the Morton Mortonson home. Opened and dedicated in late 1938, the house, the oldest in Penna. was proudly known as the birthplace of John Morton, signer of the Declaration of Independence. But in 1967 the sign was removed and the current one erected. Historian, Ruth L. Springer in her 1967 booklet, "John Morton in contemporary records" proved beyond any doubt he was not born there and the sign came down. So the state of Pennsylvania can make mistakes, imagine that.
Local groups are the worst as far as mistakes go. One local boro gives out house plaques every year for various reasons, including age. Now please understand, getting the age of when a house was built is not easy. PERIOD. But several of the plaques had really bad errors.
In the one case the 1892 atlas for the boro would have solved the problem, the house was not on the map and the street had yet to be opened by the boro. In another boro they played it safe saying the house was built sometime before 1870, but both the1870 and 1875 atlas maps clearly show the house had not been built. Lastly of course, just ask!! While doing a house tour awhile back the church I was at had a plaque from the local historical society. What surprised me was all the general information on the plaque, founded about 1850, built about 1852, dedicated c.1853. I asked the church minster if the old records had been destroyed and he said no, they had all the dates and dedication information. The historical society had just shown up one day and put the plaque on the church and had never asked for any information. The minster could not understand why they had not called the office, a church history booklet had all the information. Every historian makes mistakes, me included, but take the time, ask and do some research!