Moved from Grasshoppers, Crickets, Katydids.

"...on Willamette river. County..."

but I'm completely certain which species.

"Officially" in this country, and apparently in Australia too, a "locust" is a species of "grasshopper" that migrates, but in every day usage the names are interchanged freely. You are more likely to hear an "old-timer" call them locusts than a young person, because back when they learned the name, all the books and most people called them locusts (especially the dirt colored ones). However, in the early 1900's that became "improper" and locust was restricted to use for migratory species in government publications. Now you rarely see "locust" used in print except for really destructive species (like the "Plague Locust" of Africa or the locust swarms that we used to have in the US). In Britain a grasshopper can also be what we would call a Katydid here, and you hear people call the brown ones with colored wings "locust" much more often. So, locust / grasshopper - pretty much the same thing, and not applied the same by everybody. Lots of people call cicadas "locusts" too. The fat ones with clear wings that sit in the trees and bushes and tick or buzz and that can not jump - the books say that is wrong, but everyday usage begs to differ.

This particular one is probably Trimerotropis pallidipennis, but I'm not 100% certain (pretty sure though). This species is actually capable of migrating in swarms, but interestingly I've never heard it called a "locust", just a grasshopper - usually "Pale-winged" or "Palid-winged" Grasshopper, derived from the scientific name, which is based on the yellowish hind tibiae. Even when it is swarming and moving though, it is usually not very destructive.

Moved from ID Request.
These both look like Dissosteira to me too, but there are a few other species out west, and I'm not sure how to tell them apart.

...I think.