Quick sanity check here, because I've seen this claim and never bothered to check.
Let's say Western Europe = Germany, Austria, Italy, and everything west of them, i. e. Benelux, France, Switzerland, Spain, Portugal, Great Britain (= UK - Northern Ireland). (I'm including the UK and excluding Ireland because there are rail connecctions from Britain to the mainland but not from Ireland to Britain. I'm excluding Denmark because isn't that really Scandinavia?)
Total population: Germany = 84m, France = 68m, Britain = 66m, Italy = 59m, Spain = 47m, Netherlands = 18m, Belgium = 12m, Portugal = 10m, Austria = 9m, Switzerland = 9m, Luxembourg = 1m. Total is 383m.
Total area, in km^2: Germany = 358k, France = 551k, Britain = 228k, Italy = 301k, Spain = 499k, Netherlands = 41k, Belgium = 31k, Portugal = 88k, Austria = 84k, Switzerland = 41k, Luxembourg = 3k. Total is 2225k.
So the population density of western Europe is about 172/km^2 or 445/mi^2.
The only states this dense are DC, New Jersey, Rhode Island, Connecticut, Maryland, Delaware; New York and Florida are just under the cutoff.
If I've done the math right, DC + NJ + RI + MA + CT + MD + DE + NY + PA + OH (74m people/429k km^2) is the largest contiguous bunch of states which is over 172 people/km^2.
If we take the east to be everything east of the Mississippi, I get 190m people in 2.301m km^2, or 82 people/km^2. If we add in CA + OR + WA that actually drags down the density a bit.
So the densely populated bits of the Northeast/mid-Atlantic are as densely populated as Western Europe. But the eastern US as a whole isn't.
I agree that those pairs of cities you mentioned should have better connections between them though.
Let's say Western Europe = Germany, Austria, Italy, and everything west of them, i. e. Benelux, France, Switzerland, Spain, Portugal, Great Britain (= UK - Northern Ireland). (I'm including the UK and excluding Ireland because there are rail connecctions from Britain to the mainland but not from Ireland to Britain. I'm excluding Denmark because isn't that really Scandinavia?)
Total population: Germany = 84m, France = 68m, Britain = 66m, Italy = 59m, Spain = 47m, Netherlands = 18m, Belgium = 12m, Portugal = 10m, Austria = 9m, Switzerland = 9m, Luxembourg = 1m. Total is 383m.
Total area, in km^2: Germany = 358k, France = 551k, Britain = 228k, Italy = 301k, Spain = 499k, Netherlands = 41k, Belgium = 31k, Portugal = 88k, Austria = 84k, Switzerland = 41k, Luxembourg = 3k. Total is 2225k.
So the population density of western Europe is about 172/km^2 or 445/mi^2.
The only states this dense are DC, New Jersey, Rhode Island, Connecticut, Maryland, Delaware; New York and Florida are just under the cutoff.
If I've done the math right, DC + NJ + RI + MA + CT + MD + DE + NY + PA + OH (74m people/429k km^2) is the largest contiguous bunch of states which is over 172 people/km^2.
If we take the east to be everything east of the Mississippi, I get 190m people in 2.301m km^2, or 82 people/km^2. If we add in CA + OR + WA that actually drags down the density a bit.
So the densely populated bits of the Northeast/mid-Atlantic are as densely populated as Western Europe. But the eastern US as a whole isn't.
I agree that those pairs of cities you mentioned should have better connections between them though.