From wiki: “The main goal of this project, done in 2006, was to pay homage to the brave and determined men and women that somehow manage, without the help of any supernatural power, to work many hours in extreme conditions for low wages which are saved at great cost and sacrifice and sent to families and communities in Mexico as remittances, which is used to help their families that are back home to survive.”
There was a sign at the beginning of the pictures telling the name, occupation, home country, and the amount of money the person sends home every month.