This mystery location is a real doozy. I have not a clue as to its whereabouts. Though the lack of a hillside in the distance may indicate it being on the westside of the river. Photo is from 1973. Enlarged for your convenience is the address number.
Update: Reader PMC successfully located this as 7453 SW Fulton Rd, Portland. Picture below. Good job, I never would have assumed it would be that easy!