I wondered if you (or anyone) would catch that hyphen. It was deliberate. The pedantic side of me would justify it on the grounds that when an attributive adjective is made from a noun phrase, the constituents are properly linked by a hyphen. (In other words, "I like chocolate milk" but "Her skin was of a chocolate-milk complexion".) However, the poem in question provides a different justification, since it dates from a time (presumably the 1920's—or 1920s if you want to quibble about the apostrophe ;-) when Sedro[-]Woolley was normally a hyphenated name; the last stanza is

So they formally buried the hatchet
And henceforth all was serene.
The two became Sedro-Woolley,
With only a hyphen between.

Seriously.

Liland