Västkustensvals, or “The West Coast Waltz”, is what is called a gammaldans tune. It is not played with a dialect peculiar to just one area of Sweden, but is rather a generic type of waltz.
Gammaldans is translated as “old-time dancing”, and is the kind of dancing done by both urban and rural people all over Sweden. The types of dances that fall into this category are Waltz, Polka, Snoa, Schottische, and Hambo, with an occasional extra thrown in.
Gammaldans bands have been popular for over a century, and many early records were made of such bands.
Västkustensvals has maintained its popularity with gammaldans musicians (especially accordionists) for at least 80 years. It was composed by a fellow nemed Harry Blomqvist, probably in the 1930’s maybe before that. Probably because of recordings, it became popular in America, too, among old-time fiddlers and accordionists, mostly in the Scandinavian-settled areas.
In 1939 it was recorded by the great Carl Jularbo band, with the words sung along.
Here is a YouTube recording of it being played in 1939 in the key of G. Many bands and accordionists play it in other keys, as well.