Good Question: How Are Undocumented Immigrants Counted?

MINNEAPOLIS (WCCO) -- Americans heard vastly different plans for undocumented immigrants in the United States throughout this political campaign.

Some candidates have said they want to deport only terrorists and criminals, while others say they want to force everyone living in the U.S. illegally to leave.

Despite the candidate's disagreements, they seem to agree on one thing: the number of undocumented U.S. immigrants is around 11 million.

But how is that population counted? And who are they?

"It's actually a really difficult number to come about," said Linus Chan, a clinical professor of immigration law at the University of Minnesota. "At one point it was nine million, others say it's 12 million and it really depends on how you sample and look at the population."

Chan says researchers use statistical sampling and interviews. Pew Research Center wrote an article specifically about counting this population.

"Basically, then, our estimate of unauthorized immigrants living in the country is the total number of immigrants living in the country minus the number of immigrants living here legally," said Jeffrey Passel, a senior demographer with the Pew Research Center.

The Migration Policy Institute says the largest group is from Mexico (56 percent), followed by Guatemala (6 percent), El Salvador (4 percent), Honduras (3 percent) and China (3 percent).

Chan says the people coming from Central America are more likely to leave their country due to safety rather than economic issues.

"The reason why those countries have been the biggest drivers in the Central American [countries] is because of the violence in those countries," Chan says.

The rest of undocumented population comes from other parts of Asia (11 percent), South America (6 percent), Europe/Canada/Oceania (4 percent), Africa (3 percent) and the Caribbean (2 percent).

Chan says there are many ways to become an undocumented immigrant in the U.S. They range from crossing the border illegally, to overstaying a tourist or business visa, to coming on a student visa and staying to work.

"It could be all kinds of different situations," he said. "There's a lot of people who are here undocumented that have nothing to do with the southern border or crossing the southern border."

Over the past decade, the 11 million to 12 million number has remained steady. Chan says that is likely not due to approximately a half-million people deported each year, but rather due to the poor economy in the U.S. during that time period.

About one million U.S. undocumented immigrants are children and about half have lived in the U.S. for more than ten years. An estimated five million children, who are legal U.S. citizens, have an undocumented parent.

But why do many of these people not attempt to gain legal status?

"The laws are not easy. It's extremely difficult to get legal status," Chan said.