The increase is creating opportunities on fiscal, technological, and social fronts. This doesn't come without a price though as cities are struggling to adapt as residents compete for urban resources.

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1. Lagos, Nigeria

Lagos City is Nigeria’s largest city and economic capital with a population of over 21 million.

Located along the Atlantic Ocean, it’s the 7th fastest growing city in the world according to a 2014 report by the National Population Commission of Nigeria. Unlike other states dependent on oil revenues Lagos City economy is diversified to manufacturing, transport, construction, service, wholesale, and retail sectors.

The state covers 0.4% of Nigeria’s land yet it accounts for over 60 percent of industrial and commercial ventures of the nation. A 2015 report by the Economist states that annually Lagos State generates $90 billion dollars in goods and services. If it were a country, Lagos State economy would be number 7 in Africa.

2. Cairo, Egypt

Cairo, the cradle of civilization and in the Middle East is Egypt’s largest city and its capital. With a population of over 20.4 million, the country’s population is growing at a rate of 2.6 percent annually. Cairo is Egypt’s economic hub with two-thirds of the country’s Gross Domestic Product generated in the greater metropolitan section, according to City-Data. Textile and food processing, iron and steel production, consumer good productions, are some of the job-creating sectors in the city.

It is also a vibrant hub of tourism, commerce, finance, and government services.

3. Kinshasa, DR Congo

Kinshasa is the Democratic Republic of Congo’s capital and the largest city in the country. It’s located next to the Congo River and after Paris, is the second largest French-speaking city in the world, according to CNN. Kinshasa’s population is estimated to be from 10 million to 13.3 million. According to the United Nations (UN) report on population growth in the cities of 2015, Kinshasa’s population grew at a rate of 9.2 percent.

4. Luanda, Angola

Luanda is Angola’s capital and the country’s largest city. The city’s population was recorded at 6.5 million according to preliminary data in 2014. According to a Swedish Embassy report, Luanda has the highest annual growth in population in Africa, and by 2030 will have 9 million residents. The city's seaport is a gateway to export petroleum, diamonds, iron ore, and fish products.

Among major world capitals, Luanda in recent years has gained a reputation as among the most expensive cities to live in.

5. Nairobi, Kenya

Nairobi is Kenya’s capital and the country’s largest city. It has an estimated population of about 3.5 million and with suburbs included, it has an estimated population of 6.54 million according to the World Population Review.

Nairobi is the only city in the world near a game reserve the Nairobi National Park. It’s a vibrant commerce, technology, manufacturing, industrial, and financial hub for East and Central Africa. As such Nairobi contributes 60 percent of Kenya’s Gross Domestic Product or the nation’s wealth.