 Complete the following phrase:  Iztapalapa and most of the east side of the Federal District was historically rural and poor up until the mid-20th century. Large-scale urbanization and industrialization began in the 1950s, along with high rates of migration into the borough in the 1970s. Today, it has high population density, limited infrastructure and high levels of socio economic marginalization. Social problems include homelessness, unregulated street vending, illegal building and crimes associated with the sex trade. Many live in rundown housing with deficient municipal services. The exception to this are the areas that border the boroughs of Benito Juárez, Coyoacán and Iztacalco. As of 2010, about 30 of the boroughs buildings still have damage from the 