Because Broad-winged Hawks are in full migration right now, I decided to use the explore data function on ebird.org to see the abundance and frequency of Broad-winged Hawks for this fall, thus far. I used the data that eBirders have submitted for this fall and eBird produced this map showing the frequency of Broad-winged Hawks.
As you can see by the map, Broad-winged Hawk migration is heavy on the Atlantic Flyway which explains why the numbers in Pennsylvania have been so high. More information on the Atlantic Flyway can be found here.
I have been to the local hawk watch a few days this fall and tallied over a hundred Broad-winged Hawks, but the total for the season is 1,304 individuals! There were a few days with over 400 Broad-wings! If you want to find out how migration is going at your favorite hawk watch, check out Hawkcount! More information on the Jo Hays Vista Hawkwatch near State College can be found at The Nemesis Bird blog.