All 28 of the most populated U.S. cities are sinking to some degree, largely due to excessive pumping of groundwater, according to a new satellite-based study published in the journal Nature Cities. In 25 of those cities, at least 65% of the land is subsiding. Some neighborhoods are sinking faster than others, putting buildings and roads under stress. Metropolitan Houston is sinking the fastest, with more than 40% of the area dropping more than 0.2 inch per year and 12% sinking at twice that rate. <div></div><br>