American Migration: 1776 to 2006

Migration has contributed greatly to the growth of the U.S. population. If immigration had ceased with the signing of the Declaration of Independence on July 4, 1776, the United States would be far less populous than it is today.

Assuming the country followed the same birth and death rates over the past 230 years, the U.S. population without immigration would be around 124 million, or about the size of Japan’s current population.

Due to immigration, instead of 124 million Americans, the U.S. population today is 300 million. The major part of America's population growth — 58% — has been the result of migration (that is, U.S. immigrants and their descendants).

From the founding of the country in 1776 until today, the total number of U.S. immigrants — those granted legal permanent residence in the country — is estimated at about 72 million. In comparison, the total number of births during this period is 483 million, or close to seven times as large as the number of immigrants.

Adding the total numbers of immigrants and births to the estimated population of 2.5 million Americans alive in 1776, yields a grand total of 558 million Americans who have ever lived. Of this total number immigrants represent about 13%. Also, the majority of Americans are living today at 300 million — or 54%.

Today, the total number of U.S. immigrants or lawful permanent residents is about 12 million. Another 12 million are naturalized citizens, or former immigrants. The remaining foreign-born persons residing in the United States are illegal aliens, whose numbers are also estimated around 12 million.

Taking these three groups together, the current proportion of the U.S. population foreign-born is close to 13%, which is near the historic highs of around 15% experienced by the country at the turn of the century from 1890 to 1910.

The largest flows of immigrants arriving in the United States took place at the end and beginning of the 20th century, with the 1990s ranking as the decade with the highest immigration in U.S. history. The five highest single years are: 1991 (1.8 million), 1990 (1.5 million), 1907 (1.3 million), 1914 (1.2 million) and 1913 (1.2 million).

In contrast, since the Civil War, the smallest flows of immigrants took place in the 1930s and 1940s. The five lowest years were: 1933 (23,000), 1943 (24,000), 1944 (28,551), 1942 (29,000) and 1934 (29,000).

Throughout the 19th and most of the 20th centuries, the U.S. foreign-born population was predominantly from European countries, for example Germany, Ireland, Italy and the United Kingdom. In 1900, for instance, German immigrants accounted for 26% of the foreign born, followed by immigrants from Ireland with 16%.

By 1970, however, Mexico had moved up among the top five immigrant sending countries, accounting for 8% of the foreign born. And by 1980, Mexico was in first place with 16% of the U.S. foreign born population.

According to the 2000 census, the top five countries are no longer of European origin. They are now Mexico, China, Philippines, India and Vietnam, with Mexico accounting for 30% of the foreign born.

Of the 72 million immigrants who came to America, approximately 23 million were naturalized. In other words, over the past 230 years one out of three U.S. immigrants was naturalized. The current number of U.S. naturalized citizens is about 12 million, or about half of the total number of persons ever naturalized.

The numbers of U.S. immigrants being naturalized during the past ten years are the highest in the country's history. The five highest years of naturalization are: 1996 (one million), 2000 (889,000), 1999 (834,000), 2001 (608,000) and 2005 (605,000).

Although brief, another peak naturalization period was near the close of the World War II, with a high of 442,000 naturalized in 1944. This peak was followed some years later by very low levels of naturalization — 55,000 in 1951.

Today, approximately 600,000 U.S. immigrants are naturalized annually. In 2005, the top ten origin countries for persons naturalized, accounting for about half of the total, were Mexico (77,089), Philippines (36,673), India (35,962), Vietnam (32,926), China (312,708), Dominican Republic (20,831), South Korea (12,223), Jamaica (13,674), El Salvador (12,174) and Columbia (11,396).

The transition from legal permanent resident to U.S. citizen takes a number of years. Currently, the median number of years of U.S. residence between legal immigration and naturalization is around eight years.

In addition, not all U.S. immigrants become naturalized. For instance, among those 16 years and over who became legal permanent residents between 1973 and 1989, 58% had naturalized by the end of 2005.

Most of America's projected population growth during the 21st century — about 80% — will be the direct and indirect result of migration (immigrants and their descendants).

By mid-century, for example, America's population is projected to grow to about 420 million. Without further immigration, however, the U.S. population in 2050 is expected to be closer to 320 million.