The U.S. undocumented population is growing more diverse, less Mexican

The population of undocumented immigrants in the U.S. is becoming more diverse, and Mexicans now have the smallest share they've ever had, according to a new study by the Pew Research Center.

Why it matters: Geopolitical conflicts, climate change and more sophisticated smuggling networks are driving more migrants from Central America, the Caribbean, South America, Asia, Europe and sub-Saharan Africa to make dangerous journeys to the U.S. without permission, absent many legal options for entry.

The big picture: The Pew Research Center estimates the undocumented population was 10.5 million in 2021, which is the latest available data.

• The peak in recent history was in 2007 with 12.2 million people living in the U.S. without authorization.

Details: There were an estimated 4.1 million Mexicans living in the U.S. without authorization in 2021, or 39% of the undocumented population — their lowest share in recent history.

• After Mexicans, the largest share of the unauthorized population are, in descending order, Salvadorans, Indians, Guatemalans and Hondurans.
• Immigrants from El Salvador, Honduras and Guatemala together accounted for 2 million unauthorized immigrants in the U.S. in 2021 — about 20%.

Of note: The new estimates do not reflect the past two years of historically large numbers of illegal crossings at the U.S.-Mexico border.

What they're saying: "There are more unauthorized Mexicans (migrants) going back to Mexico than coming," Jeffrey Passel, a senior demographer at Pew Research Center and author of the report, tells Axios.

• That decrease comes amid improved conditions and lower birth rates in Mexico, he says.
• The decline could also be blamed on aggressive deportations by the Obama administration, Passel says.
• Those stepped-up deportations earned President Obama the title "deporter-in-chief" by critics and immigrant activists.
• "On the other hand, we're getting unauthorized immigrants from all parts of the world now in ways that we didn't used to," Passel adds..

State of play: Immigration is expected to be a crucial issue in the upcoming 2024 presidential election thanks in part to a surge of migrants at the U.S.-Mexico border, which has led to blowback against the Biden administration from both sides and increasingly harsh anti-immigrant rhetoric.

• Last month, former President Trump said undocumented immigrants were "poisoning the blood of our country," language which experts say echoes that of white supremacy and Adolf Hitler.
• A divided, dysfunctional Congress will make it difficult for any sweeping immigration reforms to pass. Still, both the House and the Senate are expected to at least try to link significant emergency border security funds with Ukraine aid after the Thanksgiving break.

Zoom in: Four states saw major changes in the undocumented population from 2017 to 2021.

• Florida saw the biggest increase, or 80,000 more people, during that time period, followed by Washington which saw an increase of 60,000 people.
• California experienced the largest decrease — a loss of 150,000 immigrants, followed by Nevada which saw 25,000 fewer.

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