Top left:Immigration checkpoints dot the highways and passengers are subject to "random" questioning and searches. It is widely believed that many drivers tip officials off to the presence of undocumented immigrants in their buses and taxis in exchange for a percentage of the money extorted from the immigrants.

Bottom left:The market in Cuidad Hidalgo consists of several storage structures where an army of tricycle taxis wait to shuttle goods and people through the market.  Corruption is rampant with many merchants and officials involved in the drug trade and movement of undocumented immigrants.

Top centre: A pigeon covered statue of Benito Juarez --Mexico's first, and only, full-blooded indigenous president --sits just off Tapachula's main plaza. Inscribed behind the statue is Juarez's most famous quote which reads: "Among individuals, as among nations, respect for the rights of others is peace."

Bottom centre: Raúl Vargas, 52, of Guatemala, stands between two boxcars in the Ixtapec railyard.

Bottom right: Immigrants bound for the United States board a raft on the Guatemalan side of the Sachuite River.