Many Americans can trace their ancestral roots to the “great wave” of immigration that occurred during the late 1800s and early 1900s. This is not surprising, as the foreign-born population grew rapidly during this period, doubling in size from 6.7 million in 1880 to 14.2 million in 1930. Between 1880 and 1930, the foreign-born population represented between 12 and 15 percent of the total population.

As immigration to the United States slowed after 1930 and the resident foreign-born population either died off or emigrated, the size of that population continued to decline, falling to 9.6 million in 1970, the lowest level in the 20th century. Less than 5 percent of the total population in 1970 – or less than one in 20 people – were foreign-born.

However, over the last four decades, the United States has experienced what many are calling the “second great wave” of immigration. Since 1970, the foreign-born population has continuously increased in size and as a percentage of the total U.S. population. The foreign-born population quadrupled after 1970, reaching 40.0 million by 2010, and about 13 percent of the total population – or one in eight – were foreign-born.

Once again, the country is approaching a percentage of foreign-born not seen since the late 1800s and early 1900s. Will this proportion continue to increase, perhaps exceeding the high of nearly 15 percent achieved in both 1890 and 1910?

At the moment, it is too early to tell. There is some evidence to suggest that the growth of the foreign-born population may be slowing, but even that is tenuous at this point. For example, according to the American Community Survey, the size of the foreign-born population grew by only 450,000 between 2011 and 2012, reaching 40.8 million. Also, between 2008 and 2012, the number of new arrivals – as measured by the number of foreign-born who reported they were living abroad the year before being surveyed – has remained at about 1 million each year.

Data collected in the next few years by the American Community Survey will help determine if the second great wave will continue to swell or if it has already crested.

For more information on the foreign-born population, please see the new report released today Noncitizens Under Age 35: 2010-2012.