The United States is locked in debate over immigration. The state of Arizona recently enacted legislation that encourages local police to check the immigration status of people who were stopped for other reasons – and requires immigrants to produce proof of their legal status on demand.

The Obama administration has criticized the law, church groups have protested that it is discriminatory, and a federal court has issued a temporary injunction, ruling that immigration is a federal issue. Regardless of the outcome of the legal case, the Arizona law has proven to be popular in other states, and represents the rising importance of immigration as a political issue.

If the US turned inward and seriously curtailed immigration, there would be serious consequences for America’s position in the world. With its current levels of immigration, America is one of the few developed countries that may avoid demographic decline and keep its share of world population, but this might change if reactions to terrorist events or public xenophobia closed the borders.

Fears over the effect of immigration on national values and on a coherent sense of American identity have existed since the nation’s early years.

The nineteenth-century "Know Nothing” Party was built upon opposition to immigrants, particularly the Irish. Asians were singled out for exclusion from 1882 onward, and, with the Immigration Restriction Act of 1924, the influx of immigrants slowed for four decades.

During the twentieth century, the nation recorded its highest percentage of foreign-born residents in 1910 – 14.7% of the population. Today, 11.7% of US residents are foreign born.

Despite being a nation of immigrants, more Americans are skeptical about immigration than are sympathetic to it. Depending on the poll, either a plurality or majority wants fewer immigrants. The recession exacerbated such views, and in 2009 half of Americans favored reducing legal immigration, up from 39% in 2008.

Both the numbers and origins of the new immigrants have caused concerns about immigration’s effects on American culture. Data from the 2000 census show a soaring Hispanic population, owing largely to waves of new immigrants, legal and illegal. Indeed, demographers predict that in 2050 non-Hispanic whites will be only a slim majority of US residents. Hispanics will be 25%, African-Americans 14%, and Asians 8%.

Most of the evidence suggests that the latest immigrants are assimilating at least as quickly as their predecessors.

The need to communicate effectively, together with market forces, produces a powerful incentive to master English and accept a degree of assimilation. Modern media also help new immigrants to know more about their new country beforehand than immigrants did a century ago.

While too rapid a rate of immigration can cause social problems, proponents argue that, over the long term, immigration strengthens the power of the US. Indeed, 83 countries and territories, including most developed countries, currently have fertility rates below the level necessary to maintain a constant population level.

To maintain its current population size, Japan, for example, would have to accept 350,000 newcomers a year for the next 50 years, which is difficult for a culture that has historically been hostile to immigration.

By contrast, despite Americans’ ambivalence, the US remains a country of immigration. The Census Bureau projects that the American population will grow 49% over the next four decades.

Today the US is the world’s third most populous country; 50 years from now it is still likely to be third (after only China and India). Not only is immigration relevant to economic power, but, given that nearly all developed countries are aging and face a burden of providing for older generations, it could help reduce the sharpness of the policy problem.

In addition, even though studies suggest that the short-term, directly measurable economic benefits at the national level are relatively small, and unskilled workers may suffer from competition, skilled immigrants can be important to particular economic sectors.

A 1% increase in the number of immigrant college graduates leads to a 6% increase in patents per capita. In 1998, Chinese- and Indian-born engineers were running one-quarter of Silicon Valley’s high-technology businesses, which accounted for $17.8 billion in sales, and in 2005, foreign-born immigrants had helped start one in four American technology start-ups over the previous decade.

Equally important are immigration’s benefits for America’s soft power. The fact that people want to come to the US, together with immigrants’ upward mobility, enhances the country’s appeal. America is a magnet, and many people can envisage themselves as Americans, because many successful Americans look like people in other countries.

Moreover, connections between immigrants and their families and friends back home help to convey accurate and positive information about the US. In addition, the presence of multiple cultures creates avenues of connection with other countries, and helps create an important broadening of American attitudes in an era of globalization. Rather than diluting hard and soft power, immigration enhances both.

One senior Asian statesman, an acute long-time observer of both the US and China, concludes that China will not surpass the US as the leading power of the twenty-first century because of America’s ability to attract the best and brightest from the rest of the world and meld them into a diverse culture of creativity.

China has a larger population to recruit from domestically, but in his view, its Sino-centric culture will make it less creative than the US.

While one can understand the resistance of ordinary American citizens to competition from foreign immigrants during a period of high unemployment, it would be ironic if the current debate were to lead to policies that cut the US off from one of it unique sources of strength.

Joseph S. Nye, a former US Assistant Secretary of Defense, is a professor at Harvard and author of Soft Power: the Means to Success in World Politics.

Copyright: Project Syndicate, 2010.