AP PHOTOS: An Indian state prepares for a Hindu festival that's the largest such gathering on Earth

Hindus venerate rivers, and none more so than the Ganges. The faithful believe that a dip in its waters will cleanse them of their past sins. Wherever other sacred rivers flow into the Ganges, the benefits of bathing at the confluence on auspicious days increases manyfold. A devotee can hope to begin a journey to achieve Hindu philosophy’s ultimate goal — the release from the cycles of birth and death. The most propitious of these days occur in cycles of 12 years. When the time comes for Prayagraj, in the north Indian state of Uttar Pradesh, millions flock to the confluence of the Ganges, the Yamuna and the mythical Saraswati rivers during a festival called the Maha Kumbh Mela. It has become the largest such gathering of humans anywhere on Earth. In 2025, between Jan. 13 and Feb. 26, about 400 million people, more than the population of the United States, are expected to participate in the festival. Planning for such an incredible number of pilgrims can be a logistics nightmare,...