China's population has continued to grow due to a large border and a continued modernization that has seen an increase in living standards and immigration, as well as a decrease in infant mortality rates. China has the world's largest population at 1.4 billion people.
In the 1950s, China's population was as low as 560 million. The decades after World War II saw a population boom that had the census reach a billion in the 1980s due to modernization efforts. Job growth in urban areas drew immigrants from the countryside and neighboring countries, which led to an increased effort to standardize living conditions in the cities. The result was a decrease in infant mortality and an increase in life expectancy.
The shortcoming to the massive population boom was the threat of overpopulation. To prevent a shortage of resources and to facilitate a stabilized infrastructure, the One-Child Policy was issued in 1980. The policy forced most couples to have only one child or face harsh penalties. It has been successful in slowing down the growth rate of the population. However, the birth rate of the country is now lower than what is needed to maintain a stable population size. As such, China's population growth has slowed every year, and India has been projected to beat it in population size by the early 2030s.