Loren Elliott / Reuters

The U.S.-Mexico border has been a humanitarian challenge for years, throughout the Clinton, Bush, and Obama administrations. Now, the rapidly shifting policies of the Trump administration have placed the matter once again at the forefront of the nation’s attention. In a recent conversation about family separation, one of our members asked us to take a wider look at the issue. The member asked, how did the U.S.-Mexico border, now occupying what was once Mexican territory, end up where it is today? Rachel St. John, a professor of history at UC Davis who specializes in the U.S.-Mexico border, joined us on the forums to discuss these questions. We’ve included edited versions of her answers below, followed by a brief dive into The Atlantic’s history of coverage of the border region.

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