The chart above shows the population density of EU regions.  The Western EU is the most densely populated while the Northern EU is the most sparsely populated.

The chart above shows the population density of US regions.  The Northeast is clearly the most densely populated region and is so much so that it is over twice as densely populated as the next most densely populated region.

The chart above shows the population density of EU and US states.  Not surprisingly, the European Union is much more densely populated than the US is, but what is surprising is how much more densely populated the least densely populated state in the EU is than several US states.

The chart above shows the population density of US states.  Surprisingly, it is not a small state that is the most densely populated, however it does adjoin two major metropolises in New York and Philadelphia.

The chart above shows the population density of EU member states.  As Malta is such a small state, it is not surprising that its population density is so high, but what is surprising is how low Luxembourg's is.