Population

The delta is one of the most densely populated regions on earth, and includes one of the world's largest cities on its banks—Shanghai, with a density of 2,700 inhabitants/km². Because of the large population of the delta, and factories, farms, and other cities upriver, the World Wide Fund for Nature says the Yangtze Delta is the biggest cause of marine pollution in the Pacific Ocean.
The area of the Yangtze Delta incorporates twenty relatively developed municipalities in three provinces. The term can be generally used to refer to the entire region extending as far north as Lianyungang, Jiangsu and as far south as Taizhou, Zhejiang. The region includes some of the fastest-growing economies in China in recent years, and as of 2004 has occupied over 21% of China's total gross GDP.http://en.wikipedia.org/wiki/Yangtze_River_Delta#Early_History