 Complete the following phrase:  The championship was established by the then-World Wrestling Federation WWF on September 1, 1979, after inaugural champion Pat Patterson unified kayfabe the WWF North American Heavyweight and South American Heavyweight championships. It is the third-oldest championship currently active in WWE, behind the WWE Championship 1963 and United States Championship 1975, but the second-longest tenured championship, as WWE has only owned the U.S. championship since 2001. Although generally contested in the midcard at WWE shows, it has been defended in the main events of pay-per-views including WrestleMania VI, SummerSlam in 1992, the third and In Your House shows, Backlash in 2001, and at 