Depends on what do you mean by "Europe". The continent is slightly larger than the US.

Copenhagen is closer to Zurich than Chicago is to NYC. Even Paris/Berlin is closer than Chicago/NYC.

The US's major cities are not close to each other, with the exception of the North-East Corridor, and the distances involved are far larger than most corresponding distances in Europe--you have to be talking about trips between Spain and very deep into Russia to start to compare against the NYC/LA pairing.

Some data: https://news.ycombinator.com/item?id=8713324

This is exactly what I meant by my initial comment.

The East Coast and the West Coast are far away. Because the US are almost as huge as Europe :-)