Scappoose Industrial Airpark, Scappoose, OR (SPB)
Correctly identified first by Paul Anton

A busy little general aviation airport northwest of Portland, conveniently located along the I-5 corridor. Scappoose almost always has the cheapest avgas in the area -- in fact, as of this writing, their avgas is actually cheaper than the auto gas at the gas station down the street from my house in Seattle.