PPG pilot here. Part 103.17 states that class B, C, D, and the lateral area of E to the ground are prohibited. But PASC shows an Ultralight Activity Warning symbol right in the middle of a Class E to the ground. How is this possible? Maybe the class changed and the symbol was just left on the map? Commercial 737-ish [and larger cargo] planes have been flying in and out of this place every day for nearly 50 years. I can't imagine it wasn't a class E to the ground with that level of traffic any time after the 80s. Any ideas?

From CFR:

§ 103.17 Operations in certain airspace.
No person may operate an ultralight vehicle within Class A, Class B, Class C, or Class D airspace or within the lateral boundaries of the surface area of Class E airspace designated for an airport unless that person has prior authorization from the ATC facility having jurisdiction over that airspace.