Dicho,I agree with you totally about the immense popularity and influence of Hawaiian mucic, not only on popular music but also on jazz, country and blues. This was felt through the popularity of shows, such as 'Birds of Paradise' in New York in 1904, expositions, touring troupes and, later, individual recording artists such as Frank Ferera, Sol Hoopii, King Benny Nawahi etc. In respect of country music, however, the Hawaiian influence was most marked in terms of the guitar rather than vocal style. Of particular relevance were artists like Jimmy Tarlton, Cliff Carlisle and Cousin Jody. Its influence was felt through to western swing in the work of guitarists like Leon McAuliffe.
It is worth noting that the first mainland appearance of the Royal Hawaiian Band was as early as 1883 at a function for the Knights Templar's Conclave in San Francisco. Evidently, the man who first blended European styles with Hawaiian themes for them in 1870 was an imported bandmaster from the Prussian Army by the name of Henry Berger. An additional piece of music history trivia is that band's use of the saxophone in its instrumention is said to have predated its use in the US.
For a fascinating and informative article on the influence of Hawaiian music on American popular music in particular seek out the booklet accompanying Various Artists 'Honolulu to Hollywood: Jazz, Blues & Popular Specialties Performed Hawaiian Style' Old Masters CD Tom MB123. The essay is by Allan Dodge who is perhaps best known as a founding member of Robert Crumb's Cheap Suit Serenaders. You can find a track listing here:
--Stewie.