This year, the world hit a major landmark: most of the population is now living in cities. Nowhere is that trend more dramatic than in China. Just a quarter century ago, 4 out of 5 Chinese were farmers.
Now, almost half live in urban areas - and the number's expected to grow to two-thirds within a few of decades. The United States went through a similar transformation in the 19th century. But in China, it's happening faster and on a much larger scale.
The Worlds' Mary Kay Magistad begins our series on the effects and challenges of China's rapid urbanization in Shenzhen, a former fishing village turned mega-city, just across the border from Hong Kong.
All photos: Mary Kay Magistad