On May 25, 1948, a former United States Army flier entered the American Embassy in Paris, renounced his American citizenship and, as astonished officials looked on, declared himself a citizen of the world. In the decades that followed ... he remained by choice a stateless man - entering, leaving, being regularly expelled from and frequently arrested in a spate of countries, carrying a passport of his own devising, as the international news media chronicled his every move. His rationale was simple, his aim immense: if there were no nation-states, he believed, there would be no wars. Garry Davis, a longtime peace advocate, former Broadway song-and-dance man and self-declared World Citizen No. 1, who is widely regarded as the dean of the One World movement, a quest to erase national boundaries that today has nearly a million adherents worldwide, died ... in Williston, Vt. He was 91. He continued to occupy the singular limbo between citizen and alien that he had cheerfully inhabited for 65 years. Mr. Davis was not the first person to declare himself a world citizen, but he was inarguably the most visible, most vocal and most indefatigable. The One World model has had its share of prominent adherents, among them Albert Schweitzer, Jean-Paul Sartre, Albert Einstein and E. B. White. But where most advocates have been content to write and lecture, Mr. Davis was no armchair theorist: 60 years ago, he established the World Government of World Citizens, a self-proclaimed international governmental body. To date, more than 2.5 million World Government documents have been issued.