Immigrants and their American-born children last year exceeded 61 million, accounting for nearly one out of every five people living in the United States, according to research being released Monday.

The Center for Immigration Studies, which did the research, estimated the figure by analyzing data from the U.S. Census Bureau and the Bureau of Labor Statistics.

The data paint a picture of a rapidly changing country. Census figures peg the foreign-born population at 42.6 million as of December. Adding in the number of American-born children younger than 18 with at least one immigrant parent raises the total to 61.02 million — 18.9 percent of the total population.

The increase in 2015 adds to a sum that already was at an all-time high in numerical terms. “It’s been a record high number for a long time,” said Steven Camarota, the director of research for the Washington-based think tank. “We’re in record territory.”

The overall number has exploded since 1970, when immigrants and their U.S.-born children totaled 13.5 million and made up just one in 15 residents. Since then, that group has increased by 353 percent — six times as fast as the overall 59 percent population growth rate.

[lz_table title=”Immigrant Nation” source=”Center for Immigration Studies”]Immigrants & U.S.-born kids
1970,13.4M
2000,42.6M
2015,61M
|Share of overall population
1970,6.6%
2000,15.1%
2015,18.9%
[/lz_table]

While the debate over immigration normally revolves around people who have entered the country illegally, legal immigrants and their children make up three-fourths of the total. That is, not only is illegal immigration out of control, legal immigration is too.

Camarota said many of the consequences of rapid immigration — including strain on schools and hospitals, traffic congestion, competition for jobs, and increased use of government assistance programs — occur whether the immigrants came legally or not.

“Legal immigration affects those things much more than illegal immigration,” he said.

Camarota said immigrants tend to speak little or no English, and are less educated and have fewer job skills than native-born Americans. The result is a skills mismatch that results in heavier use of welfare programs. A report by the center last year found that 51 percent of immigrant-headed families use at least one government-assistance program — largely because their U.S.-born children are eligible for programs that immigrants themselves do not quality for. That compares with 30 percent of families headed by native-born Americans.

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[lz_table title=”Fastest immigration population growth” source=”Center for Immigration Studies”]1970-2015 change (immigrants & children)
Georgia,3000%
Nevada,3000%
North Carolina,2900%
Arkansas,1800%
Tennessee,1800%
Virginia,1200%
Oklahoma,1100%
South Carolina,1100%
Texas,1100%
Arizona,1000%
[/lz_table]

Camarota said about 25 percent of public schoolchildren live in immigrant families, and they comprise about one out every three people in poverty. About a third of immigrants or their children are uninsured, he added.

“What’s important about the numbers is … immigration touches so many issues,” he said.

Because immigrants are not distributed evenly across the country, some states have experienced much more rapid increases. Since 1970, the increase in immigrants and their U.S.-born children has exceeded 1,000 percent in 10 states, led by Georgia (3,058 percent) and Nevada (3,002 percent). They now make up more than a third of the total population of California, 30.4 percent of New Jersey and 28.2 percent in Nevada.

The increase in raw numbers has accelerated in recent years. Just since 2000, immigrants and their American-born children have increased by 18.4 million.

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The immigrant population — not including American-born children — hit a high of 14.8 percent of U.S. residents in 1890 and again 1910. Then, the vast majority of immigrants were from Europe, while today most are from Latin America.

The immigrant population then declined markedly after changes in the law in the 1920s and the Great Depression, eventually hitting a low of 4.7 percent in 1970.

Spurred by the Immigration and Nationality Act of 1965 and other factors, the number shot up in the following decades. The Census Bureau projects that if current trends hold, the United States will hit a record percentage of foreign-born residents by 2023 and increase for the next 35 years.