Having lived in this mossy hovel for 20 years now I feel confident in stating that Portland may be one of the least haunted cities (of its size) on earth.
Most nights i'm sat up, staring at the wall, thinking spooky thoughts and yet the closest I've come to a ghost encounter was when I got the flu so bad I started talking to my toaster as I believed it had a soul.
Anyway, sure - there's a few. Edgefield has a kind of chilly aura, like the ghosts are tickling you with their very cold fingers. But Edgefields ghosts are typical Oregonians for the most part, very quiet and passive-aggressive, mostly hiding or ghosting up the far corners of the rooms while tutting under their breath. There are lots of places with a sort of dark, queasy atmosphere though (my apartment being one) which could become future ghost homes.
Anyway, I figure the lack of ghosts is down to it being a pretty new city, I myself may stick around after my funny earth persona ceases to be, spooking up one of the mossy alcoves of this city which we all love, or hate, or just sort of put up with because moving is scary.