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U.S. Immigration History

According to Article 1, Section 2 of the U.S. Constitution, “enumeration shall be made within three years after the first meeting of the Congress of the United States, and within every subsequent term of ten years, in such manner as [Congress] shall by Law direct.” The first U.S. census of 1790 returned a total national population of 4 million. The most recently completed, in 2010, found a national population of approximately 309 million, an increase of 5225% since 1790.

Visitors to the Census Bureau website can find an up-to-date estimate of the current U.S. population (at 4:14 p.m. EST on July 11, 2012, it stood at 313,925,460). The following chart shows U.S. population growth over the past one hundred years, according to the Census Bureau:

Notice that the population trend is insistently upward. The largest decadal increases in absolute terms were also the most recent: from 1990 to 2000, the U.S. population grew by 33 million people, while from 2000 to 2010, population grew by 28 million. At 13% and 12%, however, these were not the highest decadal rates of growth in American history. For example, from 1900 to 1910, the U.S. population grew by 21%, from 76 million to 92 million, and several decades during the 19th century saw an even higher rate of growth. However, this growth was on a much lower base population. So while the U.S. grew at a somewhat higher rate over the course of the 19th century, most growth in total numbers has occurred in the 20th century. From 1900 to 2000, the U.S. population almost quadrupled, from 76 million to 281 million people.

In contrast to the steady rise in total population, immigration numbers have fluctuated throughout American history. There has always been some immigration, but immigration levels have varied greatly, particularly, in the 20th century, due to changes in immigration policy. The following chart, again based on Census Bureau figures, shows decadal immigration numbers for the past 150 years:

From about 1880 through the mid-1920s, America experi­enced an immigration boom, “the Great Wave,” during which immigration averaged 600,000 annually. This was the period during which the U.S. industrialized, creating a huge demand for factory workers. The demand was filled primarily by European immigrants; particularly, in its second half, with immigrants from southern and eastern Europe.

In 1924 and 1926, partly in response to pressure from labor unions, Congress put in place the first comprehensive quota systems to limit immigration into the U.S. For the next 40 years, from 1925 to 1965, the United States had a relatively restrictive immigration policy, which allowed 200,000 people into the country annually, on average. Demographers sometimes call this period “the Great Pause,” although at the time, most Americans thought of it as permanent.

In 1965, Congress replaced quotas that had favored immigrants from northern and western Europe, with a new, less racially-biased system, that (in theory) allotted immigration slots as a proportion of total world population. This initiated a new phase in immigration policy, in which non-European immigration predominated; with the subsequent emphasis on “family reunification,” immigration from Mexico and the rest of Latin America came to predominate.

Also in 1965 and several times thereafter, Congress further increased immigration levels, thus initiating the second Great Wave, which continues today. Between 1965 and 1990, immigration averaged one million people annu­ally — five times the average in the previous four decades. Since 1990, immigration has increased even more, to approximately 1.5 million annually (one million legal and half a million illegal). This is the highest number of annual immigrants in U.S. history, although once again, it is not the highest rate of immigration. As a percentage of total U.S. population, immigration rates were higher at the height of the first Great Wave than they are today.

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Looking at the two charts above might cause some bewilderment. How is it that the U.S. population has climbed steadily, when immigration has varied so greatly over the past hundred years? The answer is that population growth is a function both of native birth-rates and immigration. More precisely, demographers see four primary factors determining growth rates for any population: birth rates, death rates, immigration numbers and emigration numbers. All four help determine whether a population grows or declines, and by how much.

During the first Great Wave, from 1880 to the mid-1920s, America’s population grew rapidly, due to a combination of high birth rates and high levels of immigration. U.S. population increased from a little over 50 million in 1880 to 115 million in 1925. During the Great Pause, U.S. population continued to grow substan­tially—from 115 million to 194 million people—but now primarily due to high rates of natural increase. During the 1950s, for example, American women had an average of 3.5 children each, far above the 2.1 total fertility rate (TFR) necessary to maintain the population of a nation with modern health care and sanitation. Population grew, but by tens of millions less than would have been the case, if pre-1925 immigration levels had been retained.

By the 1970s, American women were averaging fewer babies — in 1975 the TFR stood at a lowest-ever 1.7; it has since risen to 2.05 — and the United States was positioned to transition from a growing to a stable population. One study found that without post-1970 immigration, the U.S. population would have leveled off below 250 million in the first few decades of this century. Germany, Italy, the United Kingdom, France, Japan and most countries in the developed world have made this “demographic transition” and either stabilized their populations, or reached a relatively slow rate of growth.

However, the United States did not take this path. Instead, Congress increased immigration rates just as birthrates fell below replacement level. This brought in tens of millions of new citizens, including many millions of women in their childbearing years, coming from countries that still had high fertility rates.

As a result, since 1965, America’s population has climbed from 194 million to 313 million people. That’s an increase of 119 million, equal to the total population of the United States in 1927. And our population continues to grow rapidly; the U.S. Census Bureau projects a U.S. population of 440 million by 2050.