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Flood Threat Rises as America’s Largest Cities Slowly Sink

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Author Waldemar Mopera

A town submerged in flood water.
A town submerged in flood water. Image via Pexels

From New York to Los Angeles—and even cities far from the ocean like Denver and Dallas—a new study has confirmed something unsettling: every one of the 28 most populous cities in the U.S. is sinking which increases the occurrence of massive floods. Slowly, steadily, and in some places, alarmingly.

While coastal cities like New Orleans and Miami have long battled subsidence (the gradual sinking of the ground), the surprise is just how many inland urban areas are now experiencing the same threat.

What’s Causing Cities To Sink?

The fields submerged in floodwaters.
The fields submerged in floodwaters. Image via Pexels

Subsidence can be triggered by natural processes, but in most urban areas, it’s being accelerated by human activity. The biggest culprits:

  • Over-pumping groundwater from aquifers, especially in dry states like Texas and California
  • Heavy construction, which compresses loose soils under the weight of buildings and roads
  • Oil and gas extraction, which can cause localized ground collapse
  • Clay-rich soils, which shrink and settle unevenly when they dry out or get saturated

In cities like Houston, land has sunk by over 3 meters (10 feet) in some areas over the last century. But newer data from satellite monitoring is showing subtle yet widespread sinking across virtually every major metro area in the country.

Yes, Even Mile-High Denver and Landlocked Dallas

You might think elevation or distance from the coast would offer some protection—but that’s not the case. Denver, sitting at over 1,600 meters (5,280 feet) above sea level, is still experiencing measurable land subsidence due to underground water drawdowns and soil compression.

“Is Your City Sinking? 28 U.S. Cities Are Sinking Now,” Source: YouTube, Uploaded: LoudScope

Dallas is sinking, too. Groundwater pumping for agriculture and urban use has created soft spots across the city. It’s not dramatic—you won’t see buildings tilting like in Venice—but it’s enough to damage pipes, roads, and building foundations over time.

The Bigger Problem: Flooding and Infrastructure Damage

As the ground sinks, everything built on it becomes more vulnerable. Roads crack, pipelines snap, and storm drains stop working as intended. Even small drops in elevation can make cities more prone to flooding, especially during major storms.

Subsidence adds to the threat of sea-level rise in coastal cities. A city like New York or Miami might see twice the flooding impact, not just from higher oceans but also from the land beneath them slowly giving way.

And since the sinking often goes unnoticed until damage appears, many cities are unprepared.

What Can Be Done?

A measuring device used to determine the level of a flood.
A measuring device used to determine the level of a flood. Image via Unsplash

Some areas, like parts of California’s Central Valley, have restricted groundwater pumping to slow the sink. Others are experimenting with re-injecting water into depleted aquifers or shifting construction practices to avoid unstable soils.

Still, with climate change intensifying storms and cities continuing to grow, the ground beneath our feet is becoming a hidden battleground.

So, yes—it’s true. All of the U.S.’s 28 largest cities are sinking. It may be slow, silent, and spread out, but the risk of widespread flooding is real. And if ignored, it could reshape how—and where—Americans live in the not-so-distant future.

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