Summer Sausage/Trail Bologna, are synonymous in my area. And yes, I mean raw cheap bulk pork sausage or a mildly flavored sausage mainly just for afat filler, as much as anything.

Hillbilly,
Spudrow is correct, many grocery stores carry it and it's usually right where the salt and spices are. I know here in OH, Kroger's has it at both Kroger's I go to.