To hear President Donald Trump tell it, the caravan is nothing more than a “lawless” mob of potentially violent criminals. But dozens of phone interviews and WhatsApp conversations with advocacy groups and migrants, as well as social media updates from groups on the ground, show that the migrants have organized a surprisingly sophisticated ruling structure, complete with everything from a press shop to a department of public works.

When the migrants needed to make public announcements, debate the best routes and vote on different plans, they established a nightly general assembly as a forum open to all, Athens-style. Their legislative floor was an abandoned truck parking lot or an unused sports stadium. Some of the migrants even took turns as communications directors, drafting press statements that were transmitted through a media group of more than 370 journalists on WhatsApp.

When a few of the men started drinking in the evenings to distract themselves, and mothers worried the noise was keeping their children awake, the general assembly set up a kind of internal police force made up of about 100 unarmed volunteers to reprimand the men with megaphones and keep them out of the migrant’s makeshift camps after the 7 p.m. curfew.