Since 2012, a team at New York University has been working on something called the Atlas of Urban Expansion. What they are doing is collecting and analyzing data related to the quantity and quality of urban growth around the world. Everything from population densities to how well the streets were laid out during each geographic expansion.

The Atlas defines a city as having at least 100,000 people, which is a commonly used benchmark. According to this definition, there were 4,245 cities on the planet as of 2010. Included in their study is a representative sample of 200 of them, all of which can be found here.

They are also, rightly, looking at each city in terms of its extrema tectorum -- the limits of its built-up area. This is as opposed to using administrative boundaries, which wouldn't be as relevant in a study like this.

I really like the animations that they created depicting urban growth from 1800 to 2014, because they show: (1) where each city started (the dark nucleus); (2) how different urban shapes emerge as a result of geography, transport, and other factors; and (3) how land consumptive many of our cities have become in recent years.

Image: Atlas of Urban Expansion

The US Census Bureau just released its population estimates for 2018. As has been the case in previous years, the counties that added the most people (largest numeric growth) are all located in the south and west. Texas holds 4 out of the top 10 spots.

Here is a Tweetstorm by Jed Kolko, the chief economist of Indeed, with a couple of graphs summarizing the findings (click through to see the full thread):

Despite the narrative that people are returning to cities and urban centers, the data is pretty clear: the flow of domestic migration within the US is largely from dense urban counties to more suburban -- and affordable -- ones. Big cities are expensive.

Back in 2008, I toured the then new Mondrian Hotel Residences in Miami. At the time, the condo units were starting at around $700 per square foot. They came furnished (design by Marcel Wanders). And you had the option of putting it in the hotel pool so that you could earn revenue on it when you weren't using it. I can't remember what sort of ROI was being quoted at the time.

After reading this WSJ article today on fractional second home ownership, I decided to pull some listings in the Mondrian to see how values have fared over the last 11 years (even though the business models are different). Here is one: a 694 square foot 1 bedroom on the market for $295,000 (or about $425 psf). The HOA fee is $1,260 per month and, according to Zillow, the last recorded sale was on September 25, 2007. It sold for $630,400 (or about $908 psf).

Most people probably like the idea of owning a second home that makes money when they're not using it and that requires absolutely no work or effort. But frankly, I have yet to come across a highly successful condo-hotel project (where the units come and go from a hotel pool) and I have yet to see any data supporting fractional ownership (or private residence clubs) as a solid long-term investment.