Walla Walla Regional, Walla Walla, WA (ALW)
Correctly identified first by Venkatesh Gopalakrishnan.

A geat big, vast place with a whole lotta pavement, Walla Walla Regional sits just a few miles inside Washington, on the edge of the flatlands where the foothills of the beautiful Blue Mountains of northeastern Oregon march down towards the Columbia. This World War II-era field is pretty quiet nowadays, but Horizon Air provides 3 flights per day between Walla Walla and Seattle.