The day after Donald Trump visited the border in Laredo, Texas, he was armed with some fresh claims about illegal immigration, including how many immigrants are actually here.

"I don't think the 11 million -- which is a number you have been hearing for many many years, I've been hearing that number for five years -- I don't think that is an accurate number anymore," Trump said on MSNBC’s Morning Joe July 24. "I am now hearing it's 30 million, it could be 34 million, which is a much bigger problem."

Host Joe Scarborough then asked Trump, "Who are you hearing that from?"

Trump replied: "I am hearing it from other people, and I have seen it written in various newspapers. The truth is the government has no idea how many illegals are here."

Is Trump right that there are 30 million or more illegal immigrants? We decided to see what the latest evidence shows.

Counting illegal immigrants

The U.S. Department of Homeland Security comes up with an estimate of the number of illegal immigrants each year, and its most recent estimate was 11.4 million unauthorized immigrants as of January 2012. That includes those who entered the United States illegally and those who overstayed their visas.

According to the department’s estimates, the number of illegal immigrants peaked around 12 million in 2007 and has gradually declined to closer to 11 million.

The Homeland Security figure is in the same ballpark as several independent organizations that study illegal immigration, including Pew Research Center (11.3 million); the Center for Migration Studies (11 million), which studies migration and promotes policies that safeguard the rights of migrants, and the Center for Immigration Studies, which advocates for low levels of legal immigration (11-12 million).

All of them arrive at their figures by subtracting known legal immigrants from the total number of foreign-born people documented in the U.S. census and then controlling for the estimated percentage of unauthorized immigrants who refuse to answer the census.

All of the researchers we interviewed found similar figures to the federal government and said that Trump’s claim was wildly inflated.

"There are, to my knowledge, no credible, research-based estimates of 30 million," said Jeffrey Passel, an expert on Hispanic immigration at the Pew Research Center. "The 11-12 million range is broadly accepted by almost all researchers and immigration advocates (regardless of perspective)."

Steven Camarota, research director at the Center for Immigration Studies, said that the total number of illegal immigrants has essentially held constant in recent years, because the number arriving has roughly balanced the number going home or getting legal status.

Could the census be missing enough illegal immigrants in its counts that the estimate is actually in Trump’s range? The experts we talked with said no.

"Even though the empirical estimates have a margin of error of maybe plus or minus a million, there is virtually no evidence that the real number could be even a few million higher than 11 million," said Robert Warren, a fellow at the Center for Migration Studies and a former demographer with the Census Bureau and the Immigration and Naturalization Service.

Camarota said that the reason the 30 million figure is unlikely is that the census asks other questions that allow researchers to estimate how good the data is -- for example, the number of births to immigrant mothers, school enrollment and death records, which helps shore up the figure. In other words, if there were three times the generally accepted number of illegal immigrants in the United States, they would show up in those other categories.

Marc Rosenblum of the Migration Policy Institute, a think tank that doesn’t take positions on immigration legislation, said that 30 million "is a totally absurd number."

"There is NO published report by a serious research organization or academic that suggests anything in the range of 30 million," he said.

So how did Trump come up with his inflated figure? We aren’t certain, since a campaign spokeswoman declined to comment. But we’ve heard others cite similar figures.

In her book Adios America, conservative columnist Ann Coulter said there are 30 million illegal immigrants. Her starting point was a 2005 article from two Bear Stearns financial advisors, who looked at the rise in money sent back to Mexico and housing permits in three New Jersey communities. Coulter emphasized that "the assumption that illegal people will fill out a census form is the most ridiculous concept I have ever heard of."

The Center for Immigration Studies disagrees with that last point.

In a recent report, the center wrote, "It is well established that illegal aliens do respond to government surveys such as the decennial census and the Current Population Survey."

Our ruling

Trump said the number of illegal immigrants in the United States is "30 million, it could be 34 million."

The Department of Homeland Security says the number of illegal immigrants was about 11.4 million as of January 2012. Other independent groups that research illegal immigration put the number between 11 and 12 million. We found no compelling evidence that the number could as high as Trump said.

Trump has provided no proof that the number of illegal immigrants is triple the widespread consensus. We rate this claim Pants on Fire.