<P> Rapid fertility reduction associated with the one - child policy has potentially negative results . For instance, in the future the elderly might not be able to rely on their children to care for them as they have in the past, leaving the state to assume the expense, which could be considerable . Based on United Nations and Chinese government statistics, it was estimated in 1987 that by the year 2000 the population 60 years and older (the retirement age is 60 in urban areas) would number 127 million, or 10.1% of the total population; the projection for 2025 was 234 million elderly, or 16.4% . According to projections based on the 1982 census, if the one - child policy were maintained to the year 2000, 25% of China's population would be age 65 or older by the year 2040 . In 2050, the number of people over 60 is expected to increase to 430 million . </P> <Dl> <Dt> Overall </Dt> </Dl> <P> China is the most populated country in the world and its national population density (137 / km) is similar to those of Switzerland and the Czech Republic . The overall population density of China conceals major regional variations, the western and northern part have a few million people, while eastern half has about 1.3 billion . The vast majority of China's population lives near the east in major cities . </P> <Dl> <Dt> Coast and eastern China </Dt> </Dl>

Where does most of the population in china live