structural:summarization, quality:correction, stylistic:tone
20th century to present

In the 20th century the phenomenal growth of the city and its environmental and political consequences dominate. In 1900, the population of Mexico City was about 500,000. The city began to grow rapidly westward in the early part of the 20th century and then began to grow upwards in the 1950s, with the Torre Latinoamericana becoming the city's first skyscraper.

The rapid development of Mexico City as a center for modernist architecture was most fully manifested in the mid-1950s construction of the Ciudad Universitaria, Mexico City, the main campus of the National Autonomous University of Mexico. Designed by the most prestigious architects of the era, including Mario Pani, Eugenio Peschard, and Enrique del Moral, the buildings feature murals by artists Diego Rivera, David Alfaro Siqueiros, and José Chávez Morado. It has since been recognized as a UNESCO World Heritage Site.

The 1968 Olympic Games brought about the construction of large sporting facilities. In 1969, the Mexico City Metro was inaugurated. Explosive growth in the population of the city started in the 1960s, with the population overflowing the boundaries of the Federal District into the neighboring State of Mexico, especially to the north, northwest, and northeast. Between 1960 and 1980 the city's population more than doubled to nearly 9 million.

In 1980, half of all the industrial jobs in Mexico were located in Mexico City. Under relentless growth, the Mexico City government could barely keep up with services. Villagers from the countryside who continued to pour into the city to escape poverty only compounded the city's problems. With no housing available, they took over lands surrounding the city, creating huge shanty towns.

The inhabitants of Mexico City faced serious air pollution and water pollution problems, as well as groundwater-related subsidence. Air and water pollution has been contained and improved in several areas due to government programs, the renovation of vehicles and the modernization of public transportation.

The autocratic government that ruled Mexico City since the Revolution was tolerated, mostly because of the continued economic expansion since World War II. This was the case even though this government could not handle the population and pollution problems adequately. Nevertheless, discontent and protests began in the 1960s leading to the massacre of an unknown number of protesting students in Tlatelolco.

Three years later, a demonstration in the Maestros avenue, organized by former members of the 1968 student movement, was violently repressed by a paramilitary group called " Los Halcones ", composed of gang members and teenagers from many sports clubs who received training in the US.

On 19 September 1985, at 7:19am CST, the area was struck by the 1985 Mexico City earthquake. The earthquake proved to be a disaster politically for the one-party state government. The Mexican government was paralyzed by its own bureaucracy and corruption, forcing ordinary citizens to create and direct their own rescue efforts and to reconstruct much of the housing that was lost as well.

However, the last straw may have been the controversial elections of 1988. That year, the presidency was set between the P.R.I. 's candidate, Carlos Salinas de Gortari, and a coalition of left-wing parties led by Cuauhtémoc Cárdenas, son of the former president Lázaro Cárdenas. The counting system "fell" because coincidentally the power went out and suddenly, when it returned, the winning candidate was Salinas, even though Cárdenas had the upper hand.

As a result of the fraudulent election, Cárdenas became a member of the Party of the Democratic Revolution. Discontent over the election eventually led Cuauhtémoc Cárdenas to become the first elected mayor of Mexico City in 1997. Cárdenas promised a more democratic government, and his party claimed some victories against crime, pollution, and other major problems. He resigned in 1999 to run for the presidency.