Obon is an annual Buddhist event. Buddhists believe that the spirits of ancestors return home at this time. Because of this tradition, many corporations give their employees holidays around the August obon. These obon holidays are the only summer vacation for many workers. August obon holidays are also marked with a large homecoming rush or kisei rasshu, since those who live and work in big cities visit parents or grandparents who live in rural areas during this period. Others also take this opportunity to vacation, either in Japan or abroad. Therefore, at the beginning and end of obon holidays, the Tokyo International Airport and Tokyo Station are particularly crowded, while highways around Tokyo suffer huge traffic jams. Because of the tremendous number of travelers during this holiday, many people try to take summer vacation at other times in order to avoid the crowds. So, when compared to the past, kisei rasshu has begun to decrease.