Why are there are more salt domes in the Gulf of Mexico than on land?

GULF OF MEXICO AND CARIBBEAN

Over 500 mushroom-shaped geological structures formed as the Gulf separated from the Atlantic Ocean. As water evaporated, salts sank to the bottom, creating thick salt beds that rose in some places into domes thousands of feet tall and several miles in diameter.

this headline suggests that midterm congressional   elections are at the corner and trump administration wants to activate his base by vowing to clamp down on immigrants and immigration as trump had said during his election campaign around two years ago. when a baby is born in usa, the baby becomes citizen of usa for 85 years and trump wants to end this rule of birthright citizenship to control illegal immigration and this what he said in an interview""we’re the only country in the world where a person comes in and has a baby, and the baby is essentially a citizen of the united states for 85 years, with all of those benefits,” "