Assuming you mean "the depth of this water, if confined to a cross-sectional area the size of the United States", this is one of those nice Fermi estimation pro

Assuming you mean "the depth of this water, if confined to a cross-sectional area the size of the United States", this is one of those nice Fermi estimation problems: - I know the US contains hundreds of millions of people, and the world contains a single-digit number of billions. So the US has about 10% of the world's people. - The US probably isn't particularly dense or sparse relative to other populated areas, so 1/10 the population should be 1/10 the Earth's land area. - The Earth has twice as much ocean as land, and - The ocean is a few miles deep - let's say 5 - so there's about 10 miles of ocean depth per land area. - So compressing that to 1/10th the land area suggests the oceans should cover the US to a depth of about 100 miles. The exact answer, it turns out, is about 89 miles - really close, without looking up a single piece of information! https://www.wolframalpha.com/input?i=%28332%2C500%2C000+cubic+miles%29+%2F+%28area+of+united+states%29 https://www.wolframalpha.com/input?i=%28332%2C500%2C000+cubi...