I don't know the layout of the town of Pullman, since I have only been there a few times, but I do know that downtown it is located in the bottom of a canyon. Washington State University is up the hill to the east of downtown. Several tributaries come together in the valley and canyon, to ultimately feed the Palouse River.
I have made second scans of smaller areas within some of the shots, to give a better idea of what was going on at the time.
Crop: A concerned shopkeeper mans the sandbags in the doorway.
Crop: A crowd surveys the event.
Looks like the muddy water has receded a bit.
Crop: Drivers ponder the idea of traveling the street.
The normally small river runs behind the gas station.
The river is between the tracks and the building, and overflows onto the street.
Crop: A closer view.
In this view the swollen river is flowing toward the photographer.
A barrier upriver.
The farmhouse at the barrier. Note the bridge over the normal location of the river, already damaged by floating debris.
So much for the sandbags!
F.J. Koppel's Milky-Way Dairy.
Another downtown shot, river flowing toward the photographer. Right billboard is for Rainier Beer.
I believe this is the low area below the University. The trailer park may have been housing to G.I.s going to school after the war.
Not a good day for these cars.
Trailers being pushed downstream by the flood.
A then-13-year-old coupe probably won't run again.
Trailers piling into each other.
More of the same, and a dog has found something interesting.
I found a video someone made from home movies, showing some of the same angles as you see in thise photos:
It's a bit dark but it starts out in this same trailer park.
While digging around I also found out that a year later an ex-G.I. lost it and started a memorable police chase. Apparently it was documented well:
This is part of the fun of collecting vintage photos: holding history in your hands, and being able to dig through public resources to learn more about the subjects.