The Kennedy Round was the sixth session of General Agreement on Tariffs and Trade (GATT) multilateral trade negotiations held between 1964 and 1967 in Geneva, Switzerland. Congressional passage of the U.S. Trade Expansion Act in 1962 authorized the White House to conduct mutual tariff negotiations, ultimately leading to the Kennedy Round. Participation greatly increased over previous rounds. Sixty-six nations, representing 80% of world trade, attended the official opening on May 4, 1964, at the Palais des Nations. Despite several disagreements over details, the director general announced the round's success on May 15, 1967, and the final agreement was signed on June 30, 1967—the last day permitted under the Trade Expansion Act. The round was named after U.S. President John F. Kennedy, who was assassinated six months before the opening negotiations.