The number of undocumented immigrants living in the United States has continually declined after hitting its peak in 2007 with a total of 12 million, according to the latest study by the Pew Research Center.

The nonpartisan institute estimates the current number of immigrant population living in the country reached a record of 40.4 million in 2011, 13 percent of the total U.S. population. Of that number, 11,100,000 are unauthorized immigrants, declining since 2007 when it reached 12 million.

Migration from Mexico, the country providing the largest number of immigrants, has also fallen. In 2010, 58 percent of immigrants living without legal status in the United States were of Mexican origin. Also, there were a million undocumented immigrants under 18, as well as 4.5 million children born in the United States, whose parents were undocumented.

According to the study, about two-thirds of undocumented immigrants have lived in America for over a decade and nearly half of the community, 46 percent, are parents of a child.

Migration from Mexico declined from 2007 in part due to the increase of border enforcement and the growing dangers that come with the illicit transit to the United States. Many undocumented Mexican workers already in the U.S. have also found few job opportunities forcing them to return to their country, The Associated Press reports.

Last year, Obama extended temporary reprieves from deportation by granting ICE prosecutorial discretion and by giving young immigrants the right to earn work permits.

Should the U.S. pass the kind of comprehensive immigration reform currently being discussed by President Barack Obama and members of congress, this number would be expected to drop.

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  • The Template: California Proposition 187 (1994)

    California's Proposition 187 was submitted to the voters with the full support of then Republican governor Pete Wilson. It essentially blamed undocumented immigrants for the poor performance of the state economy in the early 1990s. The law called for cutting off benefits to undocumented immigrants: prohibiting their access to health care, public education, and other social services in California. It also required state authorities to report anyone who they suspected was undocumented. <strong>Status:</strong> The law passed with the support of 55 percent of the voters in 1994 but declared unconstitutional 1997. The law was killed in 1999 when a new governor, Democrat Gray Davis, refused to appeal a judicial decision that struck down most of the law. Even though short-lived, the legislation paved the way for harsher immigration laws to come. On the other hand, the strong reaction from the Hispanic community and immigration advocates propelled a drive for naturalization of legal residents and created as many as one million new voters.

  • The Worst: Arizona SB 1070

    The Arizona Act made it a misdemeanor for an undocumented immigrant to be within the state lines of Arizona without legal documents allowing their presence in the U.S. This law has been widely criticized as xenophobic and for encouraging racial profiling. It requires state authorities to inquire about an individual's immigration status during an arrest when there is "reasonable suspicion" that the individual is undocumented. The law would allow police to detain anyone who they believe was in the country illegally. <strong>Status:</strong> The law was signed into law by Arizona Governor Jan Brewer on April 23, 2010. But it has generated a swirl of controversy and questions about its constitutionality. A federal judge issued a ruling that blocked what critics saw as some of the law's harshest provisions. House: 35-31 (4/12/2011)

  • Following Arizona's Footsteps: Georgia HB 87

    The controversy over Arizona's immigration law was followed by heated debate over Georgia's own law. HB 87 required government agencies and private companies to check the immigration status of applicants. This law also limited some government benefits to people who could prove their legal status. <strong>Status:</strong> Although a federal judge temporarily blocked parts of the law considered too extreme, it went into effect on July 1st. 2011. House: 113-56 Senate: 39-17

  • Verifying Authorized Workers: Pennsylvania HB 1502

    This bill, which was approved in 2010, bans contractors and subcontractors employ undocumented workers from having state construction contracts. The bill also protects employees who report construction sites that hire illegal workers. To ensure that contractors hire legal workers, the law requires employers to use the identification verification system E-verify, based on a compilation of legally issued Social Security numbers. <strong>Status:</strong> Approved on June 8th 2010. House: 188-6 (07/08/2010) <a href="http://www.flickr.com/photos/donkeyhotey/" target="_hplink">Flickr photo by DonkeyHotey</a>

  • A Spin Off of Arizona: Utah HB 497

    Many states tried to emulate Arizona's SB 1070 law. However, most state legislatures voted against the proposals. Utah's legislature managed to approve an immigration law based on a different argument. Taking into consideration the criticism of racial profiling in Arizona, Utah required ID cards for "guest workers" and their families. In order to get such a card workers must pay a fee and have clean records. The fees go up to $2,500 for immigrants who entered the country illegally and $1,000 for immigrants who entered the country legally but were not complying with federal immigration law, <a href="http://articles.latimes.com/2011/mar/06/nation/la-na-illegal-immigration-20110306" target="_hplink">according to the LA Times.</a> <strong>Status: </strong> Law went into effect on 03/15/2011 House: 59-15 (03/04/2011) Senate: 22-5 (03/04/2011)

  • The Most Comprehensive: Florida HB-1C

    Florida's immigration law prohibits any restrictions on the enforcement of federal immigration law. It makes it unlawful for undocumented immigrants within the state to apply for work or work as an independent contractor. It forbids employers from hiring immigrants if they are aware of their illegal status and requires work applicants to go through the E-verify system in order to check their Social Security number. <strong>Status: </strong>effective since October 1st, 2010

  • The Hot Seat: Alabama HB 56

    The new immigration law in Alabama is considered the toughest in the land, even harder than Arizona's SB 1070. It prohibits law enforcement officers from releasing an arrested person before his or her immigration status is determined. It does not allow undocumented immigrants to receive any state benefit, and prohibits them from enrolling in public colleges, applying for work or soliciting work in a public space. The law also prohibits landlords from renting property to undocumented immigrants, and employers from hiring them. It requires residents to prove they are citizens before they become eligible to vote. The law asked every school in the state to submit an annual report with the number of presumed undocumented students, but this part, along with others, were suspended by federal courts. <strong>Status:</strong> Approved June 2nd, 2011 House: 73-28 (04/05/2011) Senate: 23-11 (05/05/2011) <a href="http://www.flickr.com/photos/longislandwins/" target="_hplink">Flickr photo by longislandwins</a>