An earlier Vintage Portland posting showed a very similar view to this one, but focused on the northwest industrial area of town. This view shows more of the east side of the river. In this pre-Memorial Coliseum time, N. Interstate Avenue flowed uninterrupted from center-right across to upper-left, skirting some well established residential neighborhoods, all gone now. N. Williams Ave. and N. Vancouver Ave. are visible in the far upper-right corner. Also note Union Station at lower-left.
(City of Portland Archives)
Vintage Portland 
Dan, do you have any before/after photos of vanport from this same flood?
Chris, I’ll see what I can dig up.