Train carriages are unexpectedly intimate spaces. We brush elbows with strangers, united for a moment on our individual journeys, only to separate again as soon as our feet touch the platform. But what happens when there are five million people all making their own journeys every single day? In Mexico City, it takes a miracle. The city is known for its vast and sprawling population, but its ability to move all of those people around, is almost more impressive. In the face of substantial geographical and social challenges, every day the Systema de Transporte Collectivo, or simply el Metro, moves tourists and local residents alike, beneath one of the most chaotic cities in the world.

While the official population within the city limits sits at around eight million, the surrounding valley brings the total up to more like twenty-two million. Many of these residents are concentrated in a ring around the Distrito Federal (better known to locals as DF) in satellite cities in Mexico State. The locals of these sprawling barrios travel to work or school with a mix of small buses, light rail, subway, and even a cable car. Nightmarish commutes of around two hours each way in cramped and sweltering conditions are more common than not. Understandably, an efficient public transport system in a city like this is not only useful, it is essential. What’s more, the Mexico City Metro shows the world, and Mexico itself, all that this city has to offer: creativity, history and survival.

On a global scale of underground train systems, the Mexico City Metro is relatively young, with its first line opening in 1969, compared to New York’s debut in 1904 and London’s in 1863. Each day, the Metro moves an estimated five million passengers underground, and in 2015, it clocked over 623 million passengers, placing its ridership ninth in the world (behind metro systems in China, Tokyo, Moscow and New York City). A mere five pesos, or around 40 cents, will get you anywhere in the system. Prior to 2013, one could catch a ride for around 25 cents, but these additional fees have been introduced for the purpose of improving the system.

At the time of its inauguration, the Metro symbolised Mexico’s hopeful future. The country was in the middle of a 71-year period of one-party-rule that lasted from 1929—2000. This was a time of both stability and repression for the rapidly growing and urbanising Mexican people. Throughout its lifespan, the Metro has watched the country progress towards democracy. Tellingly, there is still a long way to go for both public infrastructure and transparent government in Mexico.

Nestled in a high-altitude valley, the residents of Mexico City wake each day to a thick haze of pollution. While the Metro speeds underground, what lies atop is even more complicated. The government has attempted to restrict car usage and encourage public transport, but the public are dissatisfied with the lack of investment in the Metro’s infrastructure. Car ownership has risen since 2010 and many people drive privately-owned mini buses that seem to obey only their own road rules. To counter this issue, in 2015, the government announced an investment of $US150 million to expand and modernise sustainable public transport systems in the city.

Personal safety, especially for women, remains one of the biggest problems on the Metro. Pickpocketing is common and people are often discouraged from catching trains at night. Seven out of ten women report having experienced unwanted looks, touching, or more serious violence on public transport, according to government agency Inmujeres. The widely reported “penis seat” installed on the Metro has recently drawn attention to this issue, along with posters lining carriage walls explicitly stating that sexual violence is a crime that can result in jail time. A large-scale program of restricting some train carriages to women and children only was instituted in 2008 and is enforced by highly visible police presence during peak hours. There is a lack of hard data, but anecdotal evidence suggests this program has been effective in helping women feel safer. Sadly, violent incidents still occur.

Even with all its flaws, the Mexico City Metro retains a certain charm. For example, each of the 195 stations is represented by a single icon, a system designed to help illiterate riders when the Metro first opened. A mural of Frida Kahlo and other artists and intellectuals greets you at Insurgentes station, and Aztec carvings and artefacts stand tall at many stops. Some stations overlook scenic views of the city and many retain their original architectural character from the 70s and 80s.

A trip between Pino Suárez and Zócalo takes you through Bookshop Passage: a once annual book festival that is now one of the largest and most diverse book markets in the city, boasting around 350,000 titles. In 1988, La Raza, in the north of the city, became home to the Science Tunnel. Pause here to take a moment to look up at the ceiling and the constellations will light up against the darkness of the tunnel; a rare moment of stillness amidst a large moving wave of local commuters. A section on evolution comparing human development to the Earth’s overall existence reminds one of the vastness of time; an anomalous concept in a place where the human construct of time is core to its existence.

The way Mexicans behave on the Metro reflects the way they move through the city in general: calm, purposeful and bemused by the chaos around them. For a city with such a dense population, it’s surprising that rubbish and graffiti are barely present in the Metro. Sellers, buskers and beggars roam the carriages, but the passengers treat them with kindness and respect rather than the indifference seen in many other cities. People don’t stand to the side on escalators to let those in a hurry pass, but that is probably because hardly anyone is in a hurry.

In spite of all the quirks and the chaos, people continue to catch the Metro because they have to. Little old ladies going to church, businesspeople in suits, mums on the way home from the gym, students studying for tests, teenagers moving about; they’re all transported beneath the clamouring city, disappearing and reappearing like magic. The Metro has become a part of Mexico City’s ever-evolving fabric; a work-in-progress that allows the city to function. In some places, public transport is just a way to get where you’re going. In Mexico City, it is a living part of the city that helps the people who live there move forward, together.