Shanghai with a population of more than 23 million (with over 9 million migrants), is the largest and most developed city in China. Shanghai was the largest and most prosperous city in the Far East already during the 1930′s, and has remained the most developed city in mainland China. In the past 20 years Shanghai has again become an attractive city for tourists from all over the world. The world once again had its eyes on the city when it hosted the 2010 World Expo, recording the greatest number of visitors in the event’s history.
Shanghai is split in two by the Huangpu River. The most basic division of the area is Puxi West of the river, versus Pudong, East of the river. Both terms can be used in a general sense for everything on their side of the river, but are often used in a much narrower sense where Puxi is the older (since the 19th century) city center and Pudong the mass of new (since the 1980s) high-rise development across the river.