Ok, i generally consider this parking lot the starting point for the river run. It's a seven eleven and a bunch of other places. The address is:
1 South Pennsylvania Avenue
Morrisville, PA 19067
From here its a quick jump onto 32 to start the river run. The short run is until where 32 meets 611. There is a diner there that makes for a sweet rest stop.
Then its either take 611 home or hop back on 32 and go south (i usually do the latter for the short runs) the longer runs continue past the water gap and really chap the ass.