40 per cent of illegal immigrants in the US are overstayers

According to Marc Rubio, the US Senator for Florida, the US immigration system is 'so broken' that close to half of all illegal immigrants in the country originally entered legally. During a Fox News interview on July 22, Rubio said: "We have a porous border and I'm not just talking about the border with Mexico, I mean in general. 40 per cent of illegals are here having overstayed their visas."

Illegal immigrant figures

According to Florida based publication Politifact Rubio has mentioned the fourty percent figure before, most notably during his 2010 Senate campaign. Former Florida Governor, Jeb Bush, also said it was fourty percent during a speech at the National Automobile Dealers Association [NADA] convention on 23 January, 2015.

40 per cent figure based on old report

The figure is widely used and is commonly accepted, because it is based on a calculation from the Pew Research Center – an independent 'fact tank'. A 2006 report published by the Pew Center estimated that almost 50 per cent of illegal immigrants in the US had in fact originally entered legally and then overstayed.

They originally arrived at a typical border crossing point for example, an airport, and were subjected to checks by US immigration enforcement officers and were allowed entry to the US. The source data used by the Pew Center estimated that the overstayer percentage range was between 33 and 50 per cent. The Pew Center report decided on an approximate figure of 45 per cent overall.

The source data used by the Pew Center came from a 1997 study conducted by the Immigration and Naturalization Service (INS) – a former agency of the US Department of Justice which ceased in 2003, with many of its functions transferred across to the U.S. Citizenship and Immigration Services (USCIS), U.S. Immigration and Customs Enforcement (ICE), and U.S. Customs and Border Protection (CBP).

In 1996, while attempting to determine the number of immigrants arriving and departing the US, the INS concluded that 41 per cent of unauthorized immigrants in the country at that time had in fact arrived legally.

Former INS demographer, Robert Warren – who submitted his findings as part of the 1997 report – told Politifact that trends in immigration had altered as years passed. He said: "Since 2008, more immigrants are remaining in the US after their visas have expired. However, there are fewer illegal immigrants overall."

He added: "It's generally agreed that the number of illegal immigrants residing in the US is approximately 11 million, a drop from a high of 12 million in 2007."

Now a fellow at the Center for Migration Studies, a nonpartisan think tank devoted to the study of international migration, Warren revealed that the percentage attributed to illegal overstayers 'has been consistent for the past three decades.'

Warren asserts that those crossing into the US illegally do so from about half –a-dozen countries, particularly Mexico. Illegal immigrants from other Countries in most cases entered legally and so are nearly all overstayers, he said.

Estimates of overstayer figures

In January 2003, the INS published a further report estimating the number of illegal overstayers in the US, as an update to their 1997 study. The updated version estimated that 33 per cent of the illegal immigrant population in the US in the year 2000 had initially entered legally.

Based on data from 2000, the General Accounting Office 2004 study came up with visa overstayer estimates ranging from 27 per cent to 31 per percent, up to 57 per cent.

However, Marc Rosenblum of the Migration Policy Institute – another independent think tank – said that the data produced in 2003 and 2004, from which estimates were made, has not been updated since because there's no new information to draw fresh conclusions from.

Rosenblum said that the Department of Homeland Security has developed a system for estimating unauthorized immigrants travelling by air and sea. However, there is no official methodology for recording numbers entering on land.

A spokesperson for Immigration and Customs Enforcement confirmed that no new data had been released recently in relation to the number of overstayers in the US.

Rosenblum said: "Past estimates are the only ones available to work from. Congress has been promised new information by Homeland Security, but if they have been presented they've not been made public.

He added: "For now, there's no research to refute Senator Rubio's claim. Simply put, there has been no reliable estimate since the Pew Center study."

Fourty percent figure for overstayers mostly true

Politifact concluded that, without any new statistics there's very little for analysts to utilise to come up with a new estimate. Experts say that despite illegal immigration patterns having changed in recent years the 40 per cent is still a viable estimate. Politifact therefore deemed Rubio's claim to be 'mostly true.'