If you type "two Americas map" into Google image search, you get the following top results:
Designers overwhelmingly pick the choropleth map as the way to depitct the two nations.
Now, look at these maps from the New York Times (link):
I believe the background is a relief map. Would like to see one where the color is based on the strength of support for Democrats or Republicans.
The pair of maps is extremely effective at bringing out the story about the splitting of the U.S. population. From a design standpoint, I really like it.
I love, love, love the cute annotations everywhere on the page. I imagine the designer had fun coming up with them.
Pittsburgh Puddle, Cleveland Cove, Cincinnati Slough, ...
There is an artistic (or data journalistic) license behind the way the data are processed. Most likely, a 50% cutoff is applied to determine which map a county sits atop. The analysis is at the county level so there is neccessarily some simplification... in fact, this aggregation is needed to make the "islands" and other features contiguous.
I am a bit sad that at this moment, we are so focused on what sets us apart, and not what binds us together as a nation.
PS. Via twitter, Maciej reacted negatively to these maps: "Horribly tendentious map visualization from the NYT makes the candidate who won more votes look like a tiny minority."
This is a good illustration of selecting the chart form to bring out one's message. If the goal of the chart is to show that Clinton has more votes, I agree that these maps fail to convey that message.
What I believe the NYT designer wants to point out is that the supporters of Clinton are clustered into these densely populated urban areas, leaving the Republicans with most of the land mass. (Like I said above, because of the 50% cutoff criterion, we are over-simplifying the picture. There are definitely Democrats living somewhere in Trump's nation, and likewise Republicans residing in Clinton strongholds.)