"Mapping the U.S. by Property Value Instead of Land Area"

Excellent article and graphics at CityLab.com, worth a visit, here's the crux of it:

Metrocosm’s June cartograms include one that compares the property value of NYC neighborhoods with various U.S. states. The total value of all the residential property in Kentucky ($300 billion) falls just short of the value of all the housing property in Queens ($317 billion). The housing value of the Upper East Side all by itself is greater than that of six states.

Where it gets really interesting is at the county level.

This cartogram, which compares property values between counties across the continental United States, looks like bad news from a gastroenterologist. What this in fact shows is that just a handful of counties account for the vast majority of property values in the U.S. The distortion is so severe that it doesn’t look like a map of the U.S. at all.
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I am sure this is the same for most developed countries, see for example London houses worth more than Scotland, Wales and north combined.

Half the reason is population, even if house prices were the same across the country, London has approx. the same population and same amount of housing as NI, Wales and Scotland combined. That's easy.

The kicker is that population density amplifies this (agglomeration effects), so even if London's population were only half what it is and the same as Scotland's, London housing, with lots of people and homes in a fairly small area would be worth more than housing in Scotland, scattered across a much wider area.

So if anybody says "Land Value Tax would be a tax on London", that's quite true (I'm never sure whether this is an argument for or against LVT). Within London, land in the very centre (Zone 1) would probably be half the total, and land in the City and a few streets in the West End would be half of the total of Zone 1, and so on.