Here, land prices may be higher because more people are there bidding up the prices. But its not a direct property of the individuals. So the heatmap effect is indirect.
Maybe not big point, but there it is.
If you create a map that was land value divided by population density it would be much more interesting.
The "elite Texas counties" the article refers to are really a figment of data representation. Sure, those counties have neighborhoods or small towns that are stupid expensive, but they are the exception. All of them are highly populous, though; all five dark red counties (Dallas, Tarrant, Harris, Travis, Bexar) are in the top-20 most populous counties in the US.
Not strictly, though population density is certainly a factor (and, since its total land value in each county, so is population, which -- as counties are not of uniform size -- is a separate concern from population density. And, probably more directly than either of those, Gross County Product.)
Grain consumption levels should track population pretty well across the world.
(edit: I stand corrected, but it's still notable that property value and density aren't necessarily correlated.)
Only if you assume that the "correct" value of property is determined only by population density.
Also, while it's trite to say, correlation doesn't not mean causation. Being a proxy means a causal relationship, not just a correlation. XKCD was arguing against maps that indicate a causal relationship. Each of the graphs in the comic don't just correlate with population density maps, they're the same because they're visualizing a trait that has no difference based on geography. That's in no way the case in this situation.
As you increase populations (and population densities), cities become more economically active.
http://www.nytimes.com/2010/12/19/magazine/19Urban_West-t.ht...
After two years of analysis, West and Bettencourt discovered that all of these urban variables could be described by a few exquisitely simple equations. For example, if they know the population of a metropolitan area in a given country, they can estimate, with approximately 85 percent accuracy, its average income and the dimensions of its sewer system. These are the laws, they say, that automatically emerge whenever people “agglomerate,” cramming themselves into apartment buildings and subway cars. It doesn’t matter if the place is Manhattan or Manhattan, Kan.: the urban patterns remain the same. West isn’t shy about describing the magnitude of this accomplishment. “What we found are the constants that describe every city,” he says. “I can take these laws and make precise predictions about the number of violent crimes and the surface area of roads in a city in Japan with 200,000 people. I don’t know anything about this city or even where it is or its history, but I can tell you all about it. And the reason I can do that is because every city is really the same.”
http://www-personal.umich.edu/~mejn/election/2008/countycart...
Each state gets a number of electoral vote that matches the number of Representatives and Senators in their state. The senator thing throws it off a bit, but number of reps is based on population.
Not really, though population density is correlated with high land values, so there are obvious similarities.
PS: This is really a map of wealth * population.
Iowa is huge, those 3 million people are pretty spread out
PS: https://en.wikipedia.org/wiki/Los_Angeles_County,_California is a huge blob and only has 2,100/sq mi.
Des Moines is in Polk county with a density of 751/sq mi.
Anyways, I was just pointing out that your answer of "no b/c Iowa has 3 million people" has nothing to do with population density as the question posed.
Size on the map is calculated as the sum (property value).
If we chose Des Moines to arbitrarily be a county then its population density would be really high, but it would be an even smaller chunk on the map.
Sure, you might be able to get a reasonable approximation of that map from: population * population density per mile, but population density on its own is not going to get there.
PS: As to why I said mentioned the population of Iowa in the first place, XKCD was a map of population per area. If you scale the map based on population and ignore area then it's just a population map. http://www-personal.umich.edu/~mejn/election/2012/statepop10... Note the west coast is 1/2 the size of the east cost, and texas is about the size of california.
https://xkcd.com/1138/