Do you ever get that sinking feeling? If so, pay attention because you could actually be sinking. Roughly 35 to 40% of the ground in the United States is susceptible to developing sinkholes. The page below from the U.S. Geological Survey explains how sinkholes form and includes a map showing which areas of the country are more prone to sinkhole formation:
things considered, it's somewhat surprising that no one has written
"Chicken Little II: The Ground is Falling! The Ground is Falling!"