Every Major American City Is Slowly Sinking, New Research Reveals

A comprehensive study published in Nature Cities has uncovered an alarming reality: all of America’s largest metropolitan areas are gradually sinking into the earth beneath them.

The research, which analyzed high-resolution satellite data across the 28 most populous U.S. cities, found widespread land subsidence affecting urban zones from coast to coast. While coastal cities have long worried about rising seas, this phenomenon poses unique threats to infrastructure nationwide as different parts of cities sink at varying rates – sometimes creating dangerous stress on buildings, roads, and utility systems. With approximately 34 million Americans currently living in affected areas, the findings call for urgent attention to this slow-moving but potentially destructive hazard.

Widespread Subsidence Across Urban America

The research team, led by Leonard Ohenhen from Columbia Climate School’s Lamont-Doherty Earth Observatory, employed advanced satellite technology to map vertical land movements with unprecedented precision. Their analysis covered all U.S. cities with populations exceeding 600,000.

“As cities continue to grow, we will see more cities expand into subsiding regions,” Ohenhen explained. “Over time, this subsidence can produce stresses on infrastructure that will go past their safety limit.”

The study revealed that in 25 of the 28 cities examined, two-thirds or more of their area is sinking. Among the most affected metropolitan areas, Texas cities dominate the list of fastest-sinking regions.

Texas Cities Lead in Subsidence Rates

Houston emerged as the fastest-sinking major city nationwide, with more than 40% of its area subsiding more than 5 millimeters (about 1/5 inch) per year, and 12% sinking at twice that rate. Some isolated spots are descending as much as 5 centimeters (2 inches) annually. Fort Worth and Dallas weren’t far behind in overall subsidence rates.

Other cities showing significant localized rapid sinking include areas around New York’s LaGuardia Airport and parts of Las Vegas, Washington, D.C., and San Francisco.

The primary culprit behind this widespread urban subsidence is human activity. The researchers determined that groundwater removal for human use was responsible for approximately 80% of the overall sinking, based on county-level groundwater withdrawal data.

Multiple Forces Driving the Descent

While excessive groundwater pumping emerged as the dominant factor in most cities’ subsidence, several natural forces also contribute to the phenomenon:

• Lingering effects from ancient ice sheets that once covered North America are still causing parts of the landscape to gradually settle
• The sheer weight of urban buildings may be pressing down on the earth beneath them
• Construction of newer buildings can disrupt subsurface stability of surrounding structures
• In Texas, oil and gas extraction exacerbates the subsidence problem
• Climate change-induced droughts in some regions intensify groundwater extraction

Researchers noted that even cities showing overall stability or slight upward movement can have problematic differential motion, where adjoining localities move at different rates or in opposite directions. This uneven movement can create dangerous stress on building foundations and infrastructure.

Infrastructure at Risk

Perhaps most concerning is the study’s findings about building safety. The researchers identified approximately 29,000 buildings currently located in zones where differential land motion puts them at high or very high risk of structural damage.

San Antonio faces the highest proportion of threatened structures, with 1 in every 45 buildings subject to high risk from subsidence-induced stresses. Austin (1 in 71), Fort Worth (1 in 143), and Memphis (1 in 167) follow closely behind.

While a historical analysis of 225 U.S. building collapses between 1989 and 2000 found that only 2% were directly attributable to subsidence, the factors behind 30% of collapses were classified as unknown, suggesting subsidence could have played a larger role than previously recognized.

The eight cities with the largest populations living on sinking land – New York, Chicago, Los Angeles, Phoenix, Houston, Philadelphia, San Antonio and Dallas – have experienced more than 90 significant floods since 2000, likely exacerbated by the changing topography as land subsides.

Moving Toward Solutions

What can be done to address this nationwide challenge? The researchers emphasize that potential solutions vary depending on local conditions and specific types of subsidence.

In areas where flooding is the primary concern, mitigation strategies might include land raising, enhanced drainage systems, and green infrastructure like artificial wetlands to absorb floodwaters. For zones experiencing differential motion and tilting hazards, retrofitting existing structures, implementing stricter building codes, and limiting new construction in high-risk areas could prove effective.

The researchers suggest cities should use this new detailed information to target specific solutions rather than taking a one-size-fits-all approach.

“As opposed to just saying it’s a problem, we can respond, address, mitigate, adapt,” said Ohenhen. “We have to move to solutions.”

With climate change likely to intensify droughts in many regions and population growth increasing water demand, experts warn that without intervention, subsidence rates may accelerate in coming decades. The study provides urban planners and policymakers with valuable data to identify vulnerable areas and prioritize infrastructure protection before critical thresholds are reached.