In 1950, the U.S. Congress granted Puerto Ricans the right to organize a constitutional convention via a referendum; voters could either accept or reject a proposed U.S. law that would organize Puerto Rico as a "commonwealth" under continued U.S. sovereignty. The Constitution of Puerto Rico was approved by the constitutional convention on February 6, 1952, and by 82% of voters in a March referendum. It was modified and ratified by the U.S. Congress, approved by President Truman on July 3 of that year, and proclaimed by Governor Muñoz Marín on July 25, 1952—the anniversary of the landing of U.S. troops in the Puerto Rican Campaign of the Spanish–American War, until then celebrated as an annual Puerto Rico holiday.