https://www.abovethenormnews.com/2025/05/09/americas-cities-are-sinking-the-hidden-crisis-beneath-our-feet/

America’s Cities Are Sinking: The Hidden Crisis Beneath Our Feet
By David Freeman - May 9, 2025



The ground beneath many of America’s largest cities is sinking, and it is happening faster and more extensively than most people realize. A newly published study reveals that 28 of the most populous urban centers in the United States are undergoing significant land subsidence, with entire neighborhoods dropping in elevation year after year. This process is not isolated to coastal zones. It is unfolding across inland and river-adjacent cities, affecting both major metropolises and expanding urban corridors. The cause, in most cases, is not natural geological activity but the relentless extraction of groundwater that is slowly collapsing the very foundation cities are built on.

Between 2015 and 2021, researchers used advanced satellite measurements and ground-based datasets to track how the land surface changed in every major U.S. city with a population over 600,000. The data reveals that in every city studied, at least twenty percent of the land area is currently subsiding. In twenty-five of these cities, more than sixty-five percent of the land is sinking. The result is a growing risk to infrastructure, homes, businesses, and lives, particularly in regions where water extraction from deep underground aquifers continues unchecked.

In Houston, the fastest-sinking major city in the United States, over forty percent of the city’s land is sinking at a rate faster than five millimeters per year. Twelve percent is subsiding faster than ten millimeters per year. These figures represent land loss that accumulates every year and is largely irreversible in the short term. Houston is not an outlier. In Dallas and Fort Worth, more than seventy percent of each city is sinking at a rate that exceeds three millimeters annually. New York, Chicago, Columbus, and Detroit show similarly widespread impacts, despite being located far from the arid regions often associated with ground instability.

Altogether, approximately thirty-four million people are living atop land that is actively sinking. These are not remote or rural populations. They include residents of LaGuardia Airport in New York, Northgate in Las Vegas, East Potomac Park in Washington, DC, and neighborhoods throughout San Francisco, Long Beach, and Los Angeles. The scale of exposure is staggering. New York City alone accounts for more than a quarter of the total affected population. Eight cities together, including Chicago, Los Angeles, Phoenix, and Philadelphia, account for over sixty percent of all people living on subsiding land.

Subsidence, the gradual settling or sinking of the Earth’s surface, may sound like a distant concern. It is not. The effect is invisible on a day-to-day basis, but the damage builds year after year. Cracks in building foundations. Misaligned doors and windows. Warped roads and broken water lines. Eventually, these signs become structural hazards. Buildings become unstable. Roads buckle. Flooding increases as low-lying areas dip even further below storm runoff paths or sea level. According to the study, more than twenty-nine thousand buildings in these cities are currently situated in zones of high or very high risk of structural damage due to subsidence.

The reason so much of this subsidence is happening now is directly linked to the demand for water. Groundwater extraction is the primary driver in more than eighty percent of the observed subsiding areas. As cities expand, more water is drawn from deep underground aquifers. When this water is removed faster than it can be replenished, the soil and sediment layers above collapse, causing the surface to drop. This process is especially pronounced in confined aquifer systems where the reduction in pore pressure leads to irreversible compaction.

In cities with confined aquifers such as San Diego, New York, and Memphis, researchers found strong correlations between groundwater-level decline and subsidence. In New York, for example, the probability of land sinking more than one millimeter increased sharply when groundwater levels dropped below half their lowest historical levels. These changes are not hypothetical. They have already occurred and are continuing. In San Diego’s high-permeability aquifer system, researchers observed rapid and direct land deformation in response to hydraulic changes. In contrast, cities like Washington, DC, which sit atop low-permeability bedrock aquifers, show slower but still measurable deformation trends.

Not all aquifer systems respond the same way, but the underlying relationship is clear. Where confined aquifers are being pumped beyond their limits, the land above will sink. And the sinking does not stop when the pumping stops. Once an aquifer is compacted, it cannot easily rebound. The damage is permanent within human timescales. This has implications not only for current infrastructure but also for long-term water security, land use, and urban development.

The study identified five key cities with especially high ratios of at-risk buildings: San Antonio, Austin, Fort Worth, Memphis, and Houston. In San Antonio, one in forty-five buildings falls within a high or very high structural risk zone. In Austin, the ratio is one in seventy-one. These buildings are vulnerable to what engineers call angular distortion—the uneven settlement of foundations that can lead to wall fractures, floor displacement, and, eventually, structural failure. Although high-risk zones only account for about one percent of total city land area, their importance is magnified by the density of development and the presence of critical infrastructure in those areas.

The problem is compounded by the silent nature of the hazard. Subsidence does not arrive like a flood or a wildfire. It accumulates slowly, often without visible warning until damage is already underway. This latency makes it difficult to detect and even harder to prioritize within municipal planning and budgeting frameworks. Yet the risks are not speculative. In the past two decades, numerous building collapses in the United States have occurred without clear cause. In a comprehensive review of building failures from 1989 to 2000, at least two percent were directly linked to subsidence-related issues, and another thirty percent had unknown causes. The possibility that many of these were in fact triggered or worsened by unnoticed ground movement is real and concerning.

The danger does not stop at structural failure. Land subsidence increases the risk of flooding, particularly in cities already vulnerable to heavy rainfall or storm surges. As the ground sinks, even small changes in elevation can redirect stormwater, overwhelm drainage systems, or bring low-lying areas closer to the water table. In places like Houston, New York, and Washington, DC, which have experienced frequent flooding events since 2000, this creates a dangerous feedback loop. Sinking ground exacerbates flood risk, while flood damage increases the stress on infrastructure that is already compromised by land movement.

Even cities not traditionally considered flood-prone are at risk. The problem is not just how much rain falls, but how well the land can absorb and direct it. When infrastructure sits on unstable ground, it becomes more susceptible to shifting during heavy rains. Sewer lines, water mains, and power conduits are all vulnerable to rupture. Roads can collapse under the weight of vehicles. Buildings may develop structural stress points that only manifest during severe weather events.

The implications for planning and mitigation are profound. Traditional urban development has largely assumed stable ground conditions. This assumption no longer holds. The current trajectory of groundwater use and urban expansion suggests that more cities will find themselves in the same situation as Houston or San Antonio unless aggressive changes are made. These changes may include strict groundwater management policies, investment in infrastructure reinforcement, new zoning regulations for at-risk areas, and continuous subsidence monitoring using satellite-based methods like InSAR.

One of the most alarming aspects of the study is how few cities have high-resolution monitoring systems in place. Out of the twenty-eight cities studied, only eleven had prior vertical land motion data publicly available, most of them coastal. Inland and river-adjacent cities are often overlooked, despite showing some of the highest subsidence rates. This lack of data hampers mitigation efforts and leaves planners blind to emerging risks. Without spatially detailed land motion information, it becomes difficult to know where to invest in reinforcement or when to issue warnings.

The danger is not limited to future projections. It is already unfolding. Subsidence is not a future scenario—it is an active, ongoing hazard. Cracks in sidewalks, sagging overpasses, skewed building frames, and inconsistent road grading are already being observed. In some cities, these issues have become common enough to be considered normal, but they are not benign. They are signals of a system under stress. As cities continue to expand and demand for water increases, the stress on aquifers will rise. Without intervention, the damage to infrastructure and risk to public safety will escalate.

The need for integrated responses is urgent. Cities must prioritize both mitigation—reducing groundwater extraction where possible—and adaptation—modifying infrastructure and zoning to account for unstable ground. These actions must be data-driven and tailored to local conditions. What works in San Diego may not work in Chicago. Geological conditions, aquifer structures, and development density all play roles in determining effective responses.

In areas where mitigation is not feasible, adaptation must take the lead. That may mean retrofitting vulnerable buildings, installing flexible utility lines that can accommodate ground motion, enforcing construction standards that factor in angular distortion risk, and relocating critical infrastructure away from high-risk zones. Fiscal policies, such as grants for infrastructure resilience and land-use incentives, may also be required to accelerate action.

The findings from this study are not just a warning. They are a call to action. For too long, the ground beneath cities has been treated as a stable constant. The data shows that this assumption is no longer valid. Cities across the United States are literally sinking, and in many cases, the cause is entirely avoidable. The time to respond is not in the aftermath of a collapse or flood but now—while there is still time to change course, strengthen foundations, and safeguard lives and infrastructure before the damage becomes irreversible.

Source:

Ohenhen, L. O., Zhai, G., Lucy, J., Werth, S., Carlson, G., Khorrami, M., Onyike, F., Sadhasivam, N., Tiwari, A., Ghobadi-Far, K., Sherpa, S. F., Lee, J.-C., Zehsaz, S., & Shirzaei, M. (2025). Land subsidence risk to infrastructure in US metropolises. Nature Cities. https://doi.org/10.1038/s44284-025-00240-y