Why are all of America's biggest cities sinking?

Cities sit unmoving on the landscape — a sprawling collection of roads, sidewalks, and buildings designed to last for generations. But across the United States, urban areas are silently shifting: The land beneath them is sinking, a process known as subsidence, largely because people are using too much groundwater and aquifers are collapsing. The sheer weight of a metropolis, too, compacts the underlying soil. A new study published on Thursday in the journal Nature Cities mapped the scale of this slow-motion crisis across the country. Researchers used satellites to measure how the elevation has been changing in America’s 28 most populous ..