I saw this on the Portland Marathon site today:

The 26.2 mile Portland Marathon is about to close!! We only have 84 spots left as of Tuesday July 27th. We will CLOSE ALL REGISTRATION FOR THE MARATHON once these spaces are gone. We anticipate closing within the next 48 hours. Note: When we close you may see this message although the registration process is closed.

If you haven't yet signed up, now would be a good time!

AC Holly