There are also different fares which correspond to the length of time for which the tickets are valid. These fares, with a set time established on the ticket, permit the unlimited use of the Tren Urbano and the buses of the AMA. There are four types of ticket in this category. The first offers an unlimited service for one day and costs $ US . One can add to this a weekly pass for $ US , a 30 day pass for $ US , or, the most extensive, a 90 day pass for $ US . These can be obtained from ticket machines located throughout the system and can be paid for with cash, debit cards, or Visa and MasterCard.
Sonia Nazario 's best-selling novel, "Enrique's Journey", also depicts the process and obstacles of train migration. While this book mainly focuses on the journey of one person, it speaks for the thousands of other migrants who have struggled to reunite with loved ones. Nazario describes the emotion and difficulty experienced by entire families who are separated by the necessity to become more economically stable. The dangers of crossing Central America and Mexico by train are described in explicit detail as migrants of all ages face street gangs, corrupt officials, hunger, exhaustion, discrimination, poor weather, and deadly trains.