Description:
Based on the automobiles I'd put this photo in the early- to mid-1930s.
Car 539 was one of the 145 "Pay-As-You-Enter" (PAYE) Class K American Car Co. cars the Portland Traction Company purchased between 1909 and 1911, making the Class Ks the flagships of the heyday of Portland's trolley age. If you saw a trolley from 1910-1920, it would be a Class K.
The East Ankeny 539 is seen here on Morrison and 2nd (or thereabouts). In the background you can see the old Capitol Theatre at 4th & Morrison, and behind it the back of the Corbett Building (the tall one).