The 1960 street map of Lagos, Nigeria, shows a small western-style coastal city (18) _______. Paved roads quickly turn to dirt, and fields to forest. There are few buildings over six floors high and not many cars.
No one foresaw (19) _______. In just two generations, Lagos grew 100-fold, from under 200,000 people to nearly 20 million. Today one of the world's 10 largest cities, it sprawls across nearly 1,000 sq km. Vastly wealthy in parts, it is largely chaotic and impoverished. Most residents live in informal settlements, or slums. The great majority are not connected to piped water or a sanitation system. The city's streets are choked with traffic, (20) _______ is full of fumes, and its main dump covers 40 hectares and receives 10,000 metric tons of waste a day.
But new research suggests (21) _______ may be nothing to what might take place in the next 60. (22) _______ and people move to cities at the same rate as now, Lagos could become the world's largest metropolis, home to 85 or 100 million people. By 2100, it is projected to be home to more people than California or Britain today, and to stretch hundreds of miles - with enormous environmental effects.