[aprssig] APRS "text messaging" over long distances

[Ian]

Someone smarter than me (that should be most people on this list) please
tell me how this happens.  I am on top of Mt. Greylock in western MA in my
car with a TM-D700A running WIDE2-2 and K5LTC-9 is near Dallas TX running
same setup and path in his car and we are text messaging each other in near
real-time, and getting ACKs back.  I thought WIDE2-2 was suppose to keep
things rather "local" and this is well over a 1000 miles.  Are digipeaters
keeping track of our locations and overriding paths when a message is sent?

TIA, Ian N8IK-9