Illegal immigrants account for1 in 12 U.S. births

Undocumented immigrants make up slightly more than 4% of the U.S. adult population. However, their babies represented twice that share, or 8%, of all births on U.S. soil in 2008, according to the nonpartisan Pew Hispanic Center's report.

"Unauthorized immigrants are younger than the rest of the population, are more likely to be married and have higher fertility rates than the rest of the population," said Jeffrey Passel, a senior demographer at Pew in Washington, D.C...

Amid a heated national debate over illegal immigration, some Republican politicians have been calling for changes to the Constitution's 14th Amendment, which grants citizenship to "all persons born or naturalized in the United States and subject to the jurisdiction thereof," in order to deny citizenship to children born in the U.S. to unlawful residents...

Proponents of amending the 14th Amendment, which was enacted in 1868, say it was intended to guarantee citizenship to freed slaves after the Civil War, not the offspring of illegal immigrants. Their proposals are expected to appeal to conservative Republican voters as immigration emerges as a central issue in November's elections.

GOP opponents of repealing birthright citizenship say it undermines the party's electoral prospects among Hispanics, the nation's largest minority and fastest-growing group. Generally, Democrats are strongly opposed to repeal.

Even that first number is striking:  4% of the U.S. population are undocumented immigrants.  More details at the Wall Street Journal.