On this blog, we often talk about city building in the context of doing things to help improve a city -- whether that be a development project, a new public art mural, or an interesting local business. These interventions help to build a city. But even more specifically, the term has, for many, come to mean building up a city in a positive way.

But there is another way to think about city building. You can think of it in terms of building actual new cities. We've spoken about some of these before, namely this one in California and this odd one in Saudi Arabia. But apparently it is becoming more common. According to The Economist, the world is now building more new cities than it has in the last 80 or so years:

Egypt’s “New Administrative Capital” is part of a rush of city-building. Firms and governments are planning more settlements than at any time in the post-war period, with many already under construction. Ninety-one cities have been announced in the past decade, with 15 in the past year alone. In addition to its new capital in the north, Egypt is building five other cities, with plans for dozens more. India is considering eight urban hubs. Outside Baghdad, Iraq, workers have just broken ground on the first of five settlements.

In some cases, it is being done as a solution to urban congestion. If this city is too expensive and unaffordable, just create a new one. This appears to be part of the idea with the above city outside of San Francisco. Of course, new cities can also be created for ideological reasons, or for political purposes, which was the case with Brazil's capital city, Brasilia.

Here, the idea was to move the federal capital away from the country's populated southeast region to a more geographically neutral location in the middle of the country. It also turns out that seeding a new city with government institutions is a good way to get one of these started. Existing cities do, after all, benefit from network effects.

History points to characteristics shared by successful projects. State institutions can help anchor cities, as Brasília (in Brazil) and Chandigarh (in India) showed in the 20th century. Although both have had problems, people in Brazil and India are voting with their feet. Brasília’s population is growing at 1.2% a year, more than double the national average. Chandigarh, a state capital, is now India’s fourth-richest region on a per-person basis.

But putting money, ego, and ideology aside, when does it actually make sense to start a new city in lieu of just expanding (or addressing the problems in) the one(s) you've already got? Population size can't be the only factor in determining whether a city is "full", because Tokyo seems to do just fine as the largest metropolitan area in the world.

If it hasn't already been done, I think this would make for an interesting research project. Until then, there's this (paywalled) Economist article.