Continued immigration constantly reshapes the demography, economy, and society of the United States. As a country of immigrants, America must respond to three fundamental immigration questions: how many immigrants should be admitted; from where and in what status should they arrive; and how should the rules governing the system be enforced?

During the 1980s and 1990s, the U.S. Congress responded to growing gaps between immigration policy and immigration reality by making major changes in immigration laws and their administration. In 1986, the United States enacted the world's largest legalization program for unauthorized foreigners and introduced sanctions on employers who knowingly hired illegal foreign workers. Instead of slowing illegal immigration, however, this program allowed more foreigners to arrive legally and illegally, which prompted another round of reforms in 1996 aimed at ensuring that new arrivals would not receive welfare payments.

On September 11, 2001, foreigners in the United States hijacked four commercial planes. Two were flown into the World Trade Center towers in New York City, bringing them down and killing 3,000 people. President George W. Bush declared war on terrorist and the countries that harbor them, and Congress enacted legislation to fight terrorism. This includes new measures for tightening procedures for issuing visas to foreign visitors, tracking foreign students and visitors while they are in the United States, and giving immigration authorities new power to arrest and detain foreigners suspected of ties to terrorism. The Immigration and Naturalization Service was abolished, and its functions of preventing illegal immigration and providing services to foreign visitors and immigrants were separated in the new Department of Homeland Security.

However, anti-terrorism measures have not slowed immigration to the United States. America is poised to remain the world's major destination for immigrants and as patterns in U.S. History suggest, most of the newcomers will soon become Americans. However, past success in integrating immigrants does not guarantee that integrating newcomers will be easy or automatic. As immigrants continue to make and remake the country, the United States must develop and immigration policy for the twenty-first century.