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- Over 33 million U.S. residents live on land that is actively sinking.
- In Phoenix, Las Vegas, Denver, and other Basin cities, groundwater pumping is a key driver.
- Houston and Dallas lead the nation in both rate and extent of urban subsidence.
- Infrastructure in Colorado River Basin cities is increasingly vulnerable to hidden damage.
Monday, May 12, 2025 — Land subsidence, which is the slow, steady sinking of Earth’s surface, has quietly become one of the most widespread and costly environmental threats facing U.S. cities. A new study published on Wednesday in
has mapped the extent of this hazard in high resolution, revealing that at least 20% of the land in every one of the nation’s 28 most populous cities is subsiding. The root cause? Groundwater extraction, particularly in the drought-prone cities of the American West.
Using six years of satellite data from 2015 to 2021, researchers calculated the vertical land motion (VLM) across urban landscapes and found that nearly 34 million Americans live on sinking ground. Cities like Houston, Dallas, and Fort Worth have the most dramatic shifts, but several key cities in the Colorado River Basin—including Phoenix, Las Vegas, and Denver—are not far behind.
Subsidence in the Colorado River Basin: Western Cities on the Decline.
Though much attention has been given to coastal cities threatened by rising seas, the inland metropolises of the Colorado River Basin are increasingly at risk due to rapid urban growth, ongoing drought, and continued groundwater pumping.
- Phoenix, Arizona: The Phoenix metro area has recorded annual subsidence rates of up to 3.5 inches (9 cm), making it one of the fastest-sinking inland cities. According to the study, “notable subsidence greater than 5 mm per year” was observed in Phoenix, with 98% of the city experiencing some level of land sinking. The region’s dependency on groundwater during long droughts has led to significant aquifer depletion.
- Las Vegas, Nevada: Subsidence in the Las Vegas Valley has also reached 3.5 inches per year in certain locations. The researchers noted two particularly vulnerable neighborhoods: Northgate and Los Prados. These areas are sinking at rates above 5 mm per year, a threshold known to heighten risks to roads, utilities, and buildings.
- Denver, Colorado: Denver may be less commonly associated with groundwater depletion, but the study revealed that more than 65% of the city is sinking, with an average rate above 2 mm per year. This puts it among the top 10 U.S. cities for widespread land subsidence.
These findings matter. According to the study’s authors, even “modest rates of urban subsidence can profoundly impact the structural integrity of buildings, roads, bridges and dams.” Over time, those effects compound and can transform a minor concern into a crisis.
The Hidden Link Beneath the Surface.
Though not every instance of subsidence is driven by human activity,…