The U.S. population has increased from about 180 million people in 1960 to more than 300 million in 2012, and experts predict that the population could climb as high as 438 million by 2050 [source: Population Reference Bureau]. But where has this increase come from, and what drives human populations to such incredible heights?
Part of the U.S. population growth can be attributed to the country's pro-natal policies, such as tax credits and incentives, which rise as the number of children in a family increases. Some argue that a large portion of the population increase can be attributed to immigration. Between 2000 and 2010, the United States granted legal permanent resident status to between 700,000 and 1.27 million immigrants each year, averaging about a million a year across the decade [source: Office of Immigration Statistics]. At the same time, while undocumented immigration is obviously difficult to quantify, the Pew Hispanic Center estimated that between 2000 and 2005, the average annual inflow of undocumented immigrants was about 850,000, though that number probably fell significantly in the late 2000s, with the United States receiving an average of about 300,000 a year between 2007 and 2009 [source: Passel and Cohn].
Unlike countries like Japan or the Netherlands, where population densities are extremely high, the U.S. has no shortage of land to support a bugeoning population. Despite the abundance of space in the states, some experts argue that unchecked population growth could bring significant harm to U.S. society as well as the global environment.
As the crowding within a country rises, so too do the rates of social problems like crime, violence, drug abuse, poverty and lack of affordable housing. Perhaps even more compelling is the effect that a dramatic increase in the U.S. population could have on the environment. The average American produces an ecological footprint many times larger than that of a person living in another country, resulting in extremely high rates of pollution, global warming potential, and waste production that can impact the entire planet.
To prevent the social and environmental problems that a continually rising population could bring, some experts have toyed with the idea of implementing a population cap. Of course, any plan aimed at reducing the population or slowing the rate of growth would have to address both fertility and birth rates as well as immigration policy. A study by the Rockefeller Commission conducted during the 1970s found that limiting immigration to 400,000 people per year, combined with tax laws and education policies that helped keep the birth rate around 2 children per couple could stabilize the U.S. population within a single generation. This type of plan would not only require curbing legal and illegal immigration, but also providing family planning services and financial incentives for families to help limit birth rates [source: Facing the Future].
China's "one-child" policy serves as one of the most widely recognized examples of an attempt to control the population growth of an entire nation. By 1970, China was the world's most populous country, with a birth rate of 5.8 children per woman. After implementing a plan to levy fines and other penalties on families with more than one child during the 1980s, China's birth rate declined to an effective rate of 1.47 children per couple by the early 21st century. While on the surface this plan appears to have succeeded in curbing population growth, it also raises significant moral and ethical issues. Throughout the 1980s and beyond, the Chinese government was accused of forcing sterilization procedures on those who had more than the prescribed number of children. Infanticide and forced abortions also remained a continuous concern throughout the period [source: Feng].
More than 25 years after the one-child policy was implemented, the long-term social and economic effects of population control are also receiving greater attention. The policy has led to a shortage of females and an overabundance of males, resulting in an increase in bachelorhood and a decline in traditional family units. It has also raised fears of how the younger generation will support and care for a much larger aging population [source: Feng]. So while it does seem possible, ethical dilemmas aside, to limit population growth by public policy, known methods often replace one set of negative consequences with another.
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