Why did China enact the one-child policy?
Short answer: Overpopulation. China has over one billion people. And although China is roughly the size of the United States, it so happens that China has a huge mountain range covering most of the country. Which means that China has very few areas where there is good soil to grow crops. If the population if China continues to grow at the rate it once did, people will starve because the land cannot produce enough food to support demand. The government also found out they were running out of water too.