On the morning of Monday, July 16, 1951, Mexico City woke up underwater. The great flood engulfed several areas of the Valley of Mexico basin. In the Historic Center, the water level was so high that people had to use wooden boats and rubber rafts to get around.

Reports from the time tell of a strong tropical storm that hit central Mexico. A powerful storm that had lasted several days left two-thirds of the capital submerged. The drainage system collapsed, and water covered narrow streets and wide avenues.

The night before, on July 15, heavy rains overwhelmed the drainage systems. By Monday morning, residents of the Historic Center were moving around on rubber rafts and wooden boats, as seen in the black-and-white photographs from that day.

Mexico City flooding 1951

At the time, the main drainage system was the Grand Canal, a monumental project inaugurated during the Porfirio Díaz era. Stretching 47 kilometers, the canal carried water from San Lázaro to the Zumpango Lagoon, and from there into the state of Hidalgo.

At the time, the main drainage system for Mexico City was the Grand Drainage Canal, built between 1885 and 1900 during the presidency of Porfirio Díaz. Construction began in 1885, and the project was officially inaugurated on March 17, 1900.

This monumental project stretched about 47 km, starting in San Lázaro, an eastern neighborhood of Mexico City, and carried water northward to the Zumpango Lagoon, located outside the city in the State of Mexico, and from there into Hidalgo state.

That day, rain accumulated in the streets and sewers, and the drainage system quickly became saturated.

Entire neighborhoods remained underwater for three long months, marking one of the most dramatic episodes in the history of the Mexican capital – an event still remembered today as “the last great flood.”

The scale of the emergency forced the city government to take unprecedented action. In the aftermath of the disaster, the Churubusco River was channeled into pipes, pumping stations and drainage plants were built, and the collector system was expanded.

This disaster also led to the start of construction on the Second Tequixquiac Tunnel, a massive underground drainage project designed to carry excess water out of the valley. Work began soon after the 1951 flood, and the tunnel was completed in 1954.

What have been the major floods in Mexico?

Rain and floods like the one in 1951 are not uncommon in the Valley of Mexico.

Mexico City is built on a former lakebed, surrounded by mountains that block natural drainage. When heavy rain hits, the aging hydraulic infrastructure is overwhelmed. The causes range from unplanned urban expansion to the excessive buildup of trash in the drains.

Since the founding of Mexico-Tenochtitlan in 1325, people have tried to contain floods with levees and dikes. Major floods have been recorded in every period of the nation’s history: pre-Hispanic, colonial, 19th-century, and modern times.

  • The flood of 1446 (Aztec Empire)
  • The flood of 1449 (Aztec Empire)
  • The flood of 1553 (Colonial era)
  • The Great Flood of 1629 (Colonial era)
  • The flood of 1856 (19th-century Mexico)
  • The last Great Flood in 1951 (Modern Mexico)

The floods of 1550 and 1580 left behind weak drainage and containment systems that were frequently looted and modified, which severely affected their efficiency. As a result, the flood of 1607 ultimately destroyed the Albarradón de San Lázaro (a major dike system).

However, none of those earlier floods had threatened the city’s viability as a whole. This led to the belief that new drainage and containment works could still protect the city. The relatively mild floods of 1615 and 1623 seemed to support that hope.

The great flood of 1629

Between September 21 and 22, 1629, heavy and prolonged rains fell continuously for forty hours. Combined with poor decisions made by the authorities, this triggered the worst flooding disaster in the city’s history. Water rose to two meters deep across most of Mexico City.

The failure of the dikes and canal systems, along with continued heavy rainfall in the years that followed, kept the water at that level until 1634. Only a severe drought finally brought the situation under control, after years of failed attempts to drain the area.

A document from INAH notes that the disaster was so severe that only a small patch of land around the Plaza Mayor – what is now Mexico City’s Zócalo – remained above water. It was dubbed “the island of dogs” because many animals took refuge there.

During this entire five-year period, the city was rendered uninhabitable.

The scale of the 1629 flood disaster was so great that the colonial authorities seriously considered moving the capital of New Spain to another region, such as Coyoacán. However, the plan was ultimately abandoned due to the high cost such a relocation would have required.