Immigrant incarceration has a long history in the US - starting with the Chinese Exclusion Acts of 1882. Brianna Nofil says it’s part of a system of mass incarceration that’s still largely intact today. And: In 2015, Levi Vonk joined one of the first migrant caravans, marching with hundreds through Mexico. It’s where he met a 37 year old computer hacker named Axel Kirshner who had just been deported from the US. The two hit it off and wrote a book together about Kirshner’s life called Border Hacker. They recently sold the rights to Hollywood to turn it into a film.

Later in the show: When it comes to human beings, there aren’t many worse than William Hanson. His career as a Texas Ranger and a top official in the US Immigration Service was marred by rampant corruption. John Weber says Hanson shaped how many US policymakers still understand the border today: as a dangerous place to be policed. Plus: From 1775 to 1898, the US had numerous opportunities to expand its territory: 23 to be exact. But while the great European powers jumped at every chance to enrich their empires, Richard Maass says America often resisted that impulse.