The cargo depends on the direction. From Mexico to Guatemala, it’s usually cans of cooking oil or bags of rice, cases of Corona and cartons of eggs. It’s mostly people going the other way, many headed for the U.S. All of it, technically speaking, is illegal, but the customs and immigration officials on the international bridge never paid much mind, allowing the Suchiate River crossings to build into the cornerstone of a thriving economy in an impoverished region.
It's going to be tough for Mexico to stop all of this, but at least they are starting to, maybe their will to do so will toughen as their cities in the north overflow with asylum seekers waiting to have their cases heard in the USA.