15 U.S.C. § 3001: Congressional findings and policy

the States should have the primary responsibility for determining what forms of gambling may legally take place within their borders; the Federal Government should prevent interference by one State with the gambling policies of another, and should act to protect identifiable national interests; and in the limited area of interstate off-track wagering on horseraces, there is a need for Federal action to ensure States will continue to cooperate with one another in the acceptance of legal interstate wagers. It is the policy of the Congress in this chapter to regulate interstate commerce with respect to wagering on horseracing, in order to further the horseracing and legal off-track betting industries in the United States. The provisions of this Act [this chapter] shall take effect on the date of enactment of this Act [ Oct. 25, 1978 ], and, except as provided in subsection (b) of this section, shall apply to any interstate off-track wager accepted on or after such date of enactment. The provisions of this Act [this chapter] shall not apply to any interstate off-track wager which is accepted pursuant to a contract existing on May 1, 1978 . The provisions of this Act shall not apply to any form of legal non-parimutuel off-track betting existing in a State on May 1, 1978 . The provisions of subsection (b) of section 5 of this Act [ section 3004(b) of this title ] shall not apply to any parimutuel off-track betting system existing on May 1, 1978 , in a State which does not conduct parimutuel horseracing on the date of enactment of this Act [ Oct. 25, 1978 ].”