How AP obtained and analyzed data on 4.5 million migrants released in the US at the border

Newly obtained data on the unprecedented surge of border crossings over the past decade is shedding light on who entered the U.S. and where they went. Here is some information on the crossings, the data on 4.5 million migrants, and how The Associated Press obtained and analyzed it.

Millions of migrants crossed the border from Mexico over the last decade and were released in the United States with notices to appear in immigration court or report to an Immigration and Customs Enforcement office.

They were released to seek asylum or similar immigration benefit on humanitarian grounds. It didn’t matter whether they arrived legally. Those who crossed the border illegally could, under U.S. law and international treaty, exercise rights to claim asylum, arguing that they fled grave danger.

Near the peak of the immigration surge, in 2023, some were told to wait 10 years for an initial court date.

Each month, the government reports how many people are released in the U.S. AP wanted to know where they went.

AP learned that agents recorded street addresses for everyone released — a self-reported destination for each immigrant.

In June 2025, AP filed a request under the Freedom of Information Act with U.S. Customs and Border Protection, seeking individual anonymized information on every person released at the Mexican border by ZIP code, nationality and other characteristics. Anticipating objections on grounds of FOIA’s privacy exemptions, AP didn’t ask for names and addresses.

CBP initially directed AP to data on its public website, but that did not provide the specifics. In its appeal, AP noted that the agency collected more detailed information.

In December, after months of back-and-forth communication, CBP produced records on 5,619,982 people arrested by U.S. Border Patrol for illegal entry from Oct. 1, 2018 to July 7, 2025. The files contained columns for nationality, age, gender, date, Border Patrol sector where they crossed, and — when applicable — ZIP code for U.S. destination.

AP excluded from its analysis people for whom no ZIP code was given and likely duplicates, reducing the count to 3,652,313. The vast majority of those without ZIP codes were likely returned to Mexico.

In May, CBP produced records for 858,537 additional migrants who came through an official port of entry from 2021 through 2024, mostly through CBP One, an online appointment app that was set up for granting humanitarian parole. President Donald Trump ended CBP One on his first day in office. The AP removed people for whom no ZIP code was given and likely duplicates.

The combined data sets totaled 4,510,850 migrants.

About 100,000 migrants in the data sets were in ZIP codes with an ICE detention center or correctional facility. For example, a ZIP code in Karnes County, Texas, showed about 14,000 migrants; Karnes County’s population is only about 15,000. AP labeled those places in its map and excluded them from its tally of 4.5 million people released in the U.S.

Some results raised questions. A ZIP code in Dallas showed nearly 19,000 Venezuelan migrants, but the area is home to only about 50,000 people. It’s possible that some migrants gave an address without ever residing or even going there. Those instances were rare.

Maps and search tools exclude any ZIP code for which results are less than 10. AP concluded that in those cases, privacy concerns outweighed any potential news value.

AP journalists visited places highlighted by the data to tell stories about some of the trends. They included the Salt Lake City area, where many Venezuelan migrants settled, and the Cincinnati area, which drew many migrants from Africa and other continents.