With so many of the races in the Portland area set up to benefit worthy causes, it shouldn't be too hard to find one that supports something you believe in. Now in its fourth year, the Cause + Event race goes a step farther and lets each runner choose (within very general guidelines) his or her own charity to benefit. Cause + Event pledges to donate at least $15 of the $35 registration fee to that charity. (Disclosure: Cause + Event was set up by former Run Oregon blogger Amy Little.)
There are 5K and 10K race options (same price) available, and the registration fee includes a tech shirt, finisher's medal, and access to the post-race expo/party featuring Hit Machine.
I ran this race two years ago and had a great time (both in terms of the experience and setting a PR); you can read my recap here if you want to know more about the race course, logistics, and so on. The race takes place in Bethany Village, which I had thought was part of Beaverton but which I now see is actually part of Portland. Part of the course follows local roads, and part is on paved trails in Bethany Meadows Park.
Cause + Event Race
When: Sunday, October 18, 2015, at 9 a.m. (10K start), 9:10 a.m. (5K start)
Where: Bethany Village, Portland, Oregon
Register: Online here ($35 for 5K or 10K)