The United States soccer league system, sometimes called the American soccer pyramid, is a series of professional and amateur association football leagues based, in whole or in part, in the United States. For practical and historical reasons, some teams from Antigua and Barbuda, Bermuda, Canada, and Puerto Rico (considered a separate country by FIFA) also compete in these leagues, although they are not eligible for the Lamar Hunt U.S. Open Cup, which is open only to teams affiliated with U.S. Soccer, and cannot represent the United States in the CONCACAF Champions League; only USSF-affiliated teams can represent the U.S. in the continental tournament.