I've always tried to consider a composer in the context of his work, rather than the country of birth, as many of them immigrated for various reasons.
Bloch wrote only a small number of pieces before arriving in the U.S. Almost all of his adult life was spent in the U.S. as an American citizen. The vast majority of his opus was penned and published in the U.S. and pretty much all of his professional activity took place in the U.S.
So I would personally consider him a Swiss born American composer.
More complicated is Gian Carlo Menotti, who was Samuel Barber's partner in life. He called himself an American composer, lived almost all his life in the U.S., and composed in the U.S. But he remained an Italian citizen, died at a home he owned in Monaco and was buried in Scotland!
What would you say of Bax? English or Irish where his spirit belonged? How about Rachmaninoff who spent much of his life in the US though his heart was very clearly Russian? Schnittke...Russian or German?
