1917 ad.
Here's a larger size.
University of Hawaii at Manoa has a whole Flickr set of vintage ukulele advertisements from the first decade of the 20th century:
Ukulele was all the rage on the mainland United States in the late 1910s and early 1920s. George E. K. Awai and his Royal Hawaiian Quartet popularized the small, guitar-like instrument when they performed at the Panama Pacific International Exposition at San Francisco in 1915.
During the ukulele craze, ukulele advertisements appeared in U.S. mainland newspapers.
1915 ad.
