In 1945, the United Nations endorsed this definition

During the interval between the two world wars, the world's international tourism income grew rapidly, so a more accurate definition is urgently needed in statistics. In an international forum held in 1936, the Statistical Experts Committee of the League of Nations proposed for the first time that "foreign tourists refer to people who leave their habitual residence to travel to other countries for at least 24 hours". In 1945, the United Nations (replacing the original League of Nations) endorsed this definition, but added the limitation of "the maximum stay time is not more than six months".