Business Insider reports the world's projected fastest-growing cities based on UN population estimates are all on one continent. <br /><br />The world population is expected to grow to 8.6 billion in 2030, and African metro areas are leading this growth. <br /><br />Africa is growing so quickly because of its increasingly large young population, the highest of any continent. <br /><br />Over 75% of its population is younger than 35.<br /><br />The world's third fastest-growing city is Kampala, Uganda. It has an estimated 2020 population of 3,928,000 and is projected to grow to 7,004,000 in 2035.<br /><br />Zinder, Niger, has an estimated 2020 population of 489,000 and is projected to grow to 1,065,000 in 2035.<br /><br />The fastest-growing city in the world is Bujumbura, Burundi. With an estimated 2020 population of 1,013,000, it's projected to grow by 123% to 2,263,000 in 2035.
