Just 30 years ago some 700 million people lived in cities. Today the number (1) at 1,800 million, and by the end of the century it will be up to 3,000 million—more than half the world’s (2) population. By the year 2000, it is said 650 million people will (3) into 60 cities of five million or more—three quarters of them in the (4) world. Only a single First World city—metropolitan Tokyo, which will have 24 million people—is (5) to be among the global top five; London, (6) second in 1950 with ten million people, will not (7) make 2000’s top 25. In places (8) rates of natural population increase (9) three percent annually—meaning much of the Third World—that (10) is enough to double a city’s population within 20 years. But (11) powerful are the streams of hopeful (12) from the countryside. What faces and confuses urban planners is the huge scale of these (13) . There have never been cities of 30 million people, (14) alone ones dependent on roads, sewer and water supplies (15) adequate for urban areas a tenth that size. And the flood of new arrivals in (16) Third World cities far overtakes the supply of jobs— (17) as modem industries put a premium on technology (18) than manpower. So it will be virtually impossible to find permanent (19) for 30 to 40 percent of the 1,000 million new city inhabitants expected by the year 2000. Despite the terrible conditions that the city newcomers face, their numbers are growing at rates as much as twice that of the cities themselves—and every step taken to improve their (20) conditions in the slums only attracts more migrants.