premise: Heavy Metal music was started in the United States.
hypothesis: Heavy metal ( or simply metal ) is a genre of rock music that developed in the late 1960s and early 1970s , largely in the United Kingdom and the United States . The new wave of American heavy metal ( commonly abbreviated as NWOAHM ) is a heavy metal music movement that originated in the United States and Canada during the early to mid-1990s and expanded most in the early to mid-2000s .