Bucks County PA has been experiencing mysterious booms since April, and to hear the media talk about it, this is an entirely local phenomenon with no real history. The sounds are typically localized rather than spreading over a wide area as would the sonic boom of a passing jet that was flying faster than the speed of sound. The booms are also accompanied by ground shudders, but they are not powerful enough to be recorded as earthquakes. One of the few ways a boom like this could be produced is if something was moving straight down at supersonic speed. Another possibility is that the booms are caused by something underground, but the fact that they migrate suggests that the sound is generated by overhead activity.
The FBI is said by local media to be investigating this incident.
Unknowncountry’s first "mysterious boom" story was posted on May 17, 1998, and you can read them all by clicking here. For the most part, these cases have not been solved.
Dreamland has also covered booms many times, starting in 2012, and subscribers can listen to them by clicking here.