A group of men in their early 20s pose for a photo in Lagos, Nigeria, on Feb. 25, 2015. Analysts are predicting that a boom in the youth population of many cities in sub-Saharan Africa will help boost economic growth. Kathleen Caulderwood

Many sub-Saharan African countries are experiencing an economic boom thanks to vast natural resources. But the region has another untapped asset that will help its growth outpace counterparts around the world -- its young people.

The demographics of the world’s biggest cities are shifting toward younger people. And according to a new report from Ernst & Young, African hubs will have an advantage, as its cities become dominated by younger people while other major hubs watch their populations age.

Researchers note that cities such as Nigeria’s capital of Lagos, Dar es Salaam in Tanzania and the Angolan capital of Luanda will experience “extremely rapid growth of their young populations.” Ernst & Young predicts that by the year 2030, 90 percent of the world’s young urban population will live in large cities in some of Africa’s fastest-growing economies.

“Young populations can help to create large and productive labor forces,” the report says, but also drive unrest in countries with underemployment and other social ills.”

However, a growing youth population is still an advantage over cities with mostly older residents, where aging citizens leave the workforce without a skilled younger workers to replace them. The phenomenon is happening in 122 of the 750 top cities around Europe, Asia and South America.

The stark contrast can provide a much-needed boost to the developing world.

“Recent shifts in the age structure towards younger populations present an unprecedented opportunity to catapult developing economies forward,” reads a recent United Nations report. “The ‘economic miracle’ experienced by East Asian economies could become a reality for many of today’s poorer countries, particularly in sub-Saharan Africa.”

Nigeria became Africa's largest economy just last year, and the World Bank recently upgraded its forecast for economic growth in Kenya this year from 4.7 percent to 6 percent. And economists at Standard Bank are expecting a boom in middle-class households across the region.

According to the U.N., policymakers must work to capitalize on the younger population to keep growth sustainable.

“Policies that empower young people, coupled with efforts to actively engage them in decisions that affect their lives and shape their future can mean the difference between a demographic trend that weighs economies down and one that buoys them,” the report says, with hopes that these countries will be able to benefit from the burgeoning “demographic dividend.”