It seems that in 1915, Hawaiian Ukulele manufacturers were mad that many Uke makers in the US were producing instruments with a “Made in Hawaii” label, even though they were not actually produced in the islands. So they called for legislation to protect local luthiers.
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According to an article in The New York Times, Hawaiians at the San Fransisco Exposition (more precisely the Panama-Pacific Exposition, which took place in San Francisco in 1915) had “infected visitors with a desire to posses” a Ukulele. As a result, large-scale production in the US began, with a “Made in Hawaii” label as standard.
They called for legislation to protect the trademark “Made in Hawaii, U.S.A.” for all instruments made in the islands and to make it a misdemeanor to use it on Ukuleles made in the US and not the islands.
The article also notes that a good Ukulele made of Hawaiian Koa could sell in 1915 for as much as $15.