I have no idea what the beam covers. I've only ever found one map that had actual coverage areas instead of just the centers, and the western boundary did indeed go right down through Lycoming and Union counties. But there's something not right about that map, because it doesn't show the Philadelphia / DC beam coming anywhere near either of us, whereas I get a better signal on it than I do on some of the CONUS transponders!
I'm in Northumberland county (east) and I only get a signal strength of 5 on TP 7. Other TP's are between 50 and 60. Check out the "HD locals for Wilkes-Barre/Scranton, PA timeframe??" thread for a lot more discussion on this. (Sorry, I tried to insert a link but apparently I havn't posted long enough to earn the privilege)
It would be interesting to see who is the fartherest west of Scranton and still gets signal on this.