The landmass of the United States saw a sudden expansion by 1 million square kilometres (more than 386,000 square miles), which is more than twice the area of Spain.
This expansion in land was not because of strange geological forces or the invasion of a foreign land but because the country had made attempts to lay claim over its surrounding ocean-floor territory.
Continental shelves cover the areas of the seabed around huge landmasses where the sea is comparatively shallow in comparison with the open ocean.
