# Update - How long does it take to build a Dallas-sized city? [duplicate]

This question already has an answer here:

Just a hypothetical question:

What if a couple of architects, young, were able to draw up plans for a city the size of, say, Dallas TX (metroplex and surrounding vicinity). They are given full support and funding (they're pretty rich themselves) and they oversee the unceasing raising of dozens of mid-sized skyscrapers and surrounding neighborhoods. How long, realistically, would it take for them to build the city and actually see it prosper? Would they be pretty old by the time the city becomes an actual city? 20 years? 50 years?

City details: approx. the size of downtown Dallas TX

Skyscraper average height: less than 100 feet mostly

Population goal: approx. 1 million people

Basically, if building a city were a designated "project", and not just something that naturally develops over time with increasing population.

Alternatively, how long would it take for them to "gentrify" an existing city, the same size, and modernize it, knock down old buildings and build new ones, etc...?

## marked as duplicate by sphennings, L.Dutch♦, Youstay Igo, Frostfyre, MormacilMay 9 '17 at 13:08

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• You shouldn't accept an answer so quickly (even mine!). If it is unanswered more people will look at it an contribute. – kingledion May 4 '17 at 3:33
• Please don't repost a question that has already been put on hold. Instead, you should edit the original question to fix whatever the issue with it was. – a CVn May 4 '17 at 8:50
• @kingledion As recently seen on meta, user should "Point out the difference. Highlight it, put it at the top, as a heading, whatever it takes, but make sure that people know about the difference of the two seemingly very similar questions up front. By having such a key difference, the two automatically are non-duplicates, because answers valid to one are not valid to the other." - adamdesign, please do it, OK? – Mołot May 4 '17 at 11:58
• Also, the "Update -" part of the title made me think OP simply didn't see the edit button. Better choice of words would be helpful - but I prefer the title to be clean, and any explanations like this done in first paragraph instead. Or last, if only it's visible and easy to spot. – Mołot May 4 '17 at 12:04
• @kingledion "Ask smaller pieces of the question", as Monica put it, is not the same thing as "repost the exact same question with a few details added". Asking smaller pieces of the question would be more like how I, back when the site was still new, took one piece out of How does one go about developing a language for a particular culture in your world? to ask the separate question For designing a vocal language for an intelligent species, how to decide on phonemes? – a CVn May 4 '17 at 12:28

# What sort of city?

You ask specifically about Dallas, Texas. This is interesting, because Dallas, along with most American cities, is unique compared to world cities due to its level of sprawl. Dallas in particular is really rivaled only by Atlanta among American cities due to its sprawl. So it is an interesting city to try to build, since no other city requires you to build outwards so far.

First, lets get some data. Dallas and Tarrant Counties, TX have an area of 4499 km$^2$ and a population of 4,177,173 at the last census; a density of 928 people per km$^2$. A similar sized but much denser US city is Boston. Suffolk, Norfolk, Middlesex, and Essex counties in MA have an area of 4605 km$^2$ and a population of 3,855,210; a density of 837 people per km$^2$. Another similar sized but denser still European city is Rome, which has 4,340,915 people in a metro area of 5352 km$^2$; a density of 811 people per km$^2$.

So Dallas is evidently more densely populated than either of its peers, why do I keep calling it low density? Lets look closer in. Dallas’s city itself is 999 km$^2$ and has 1,197,816 people. Boston and its nearest suburbs$^1$ have 2,237,072 people in 1017 km$^2$. The Rome commune, without the Cassia Flamina Municipio has 2,531,062 in 967 km$^2$. Dallas’ density is 1199, Boston is 2199, Rome is 2617.

Even closer in, it gets even more disparate. I have built a program that estimates US cities’ densities at certain areas using zip code information. Dallas’ densest 100 km$^2$ holds about 223,000 people; Boston 676,000; and Rome’s I, II, V, and VII municipios around 883,000.

# Why mention this?

There is little data available on building a city outwards. No US city with a population over a million has been founded recently (Oklahoma City is probably the most recent, in 1890) so it is hard to tell how long it takes to expand a cities footprint so large.

But you are only asking about a downtown. Dallas’ downtown isn’t very big. If you count the 100 km$^2$ that I talked about before, my calculations land 223,000 people and 299,000 jobs; good enough for 20th out of the US cities. A city that large is pretty easy to build. I will give you answer the benefit of the doubt and assume you wanted something a little more built up. Boston’s densest 100 km$^2$ has about 676,000 people and 697,000 jobs, good for 3rd in the US, after Chicago and New York. Lets see how long it takes to build a city that big.

# 20 Years

Here is a picture of Dubai:

Dubai has a lot of tall buildings. In fact, if you look at a list of them, Wikipedia list 104 buildings in Dubai over 180m. Dallas, by comparison, has 12. Going back to that first list, we can see that only one of the 104 buildings on that list was built before 1999. In 1995, Dubai's population was about 674,000; 20 years later it is around 2.4 million.

If you are interested strictly in building up, it is possible for a city to move from a provincial town of less than a million to having the 13th most highrises of any city in the world, including 22 300m buildings (the United States in total has 19), and add housing for almost 2 million people, all in about 20 years.

Footnotes:

1: Suburb list: Boston, Cambridge, Somerville, Chelsea, Malden, Everett, Brookline, Winthrop, Watertown, Revere, Belmont, Arlington, Newton, Medford, Melrose,Quincy, Milton, Saugus, Lynn, Marblehead, Swampscott, Salem, Braintree, Weymouth, Nahant, Stoneham, Winchestser, Womburn, Wakefield, Reading, Lynnfield, Peobody, Waltham, Wellesley, Needham, Dedham, Westwood, Norwood, Canton, Randolph

• Wow! Great answer! Thanks a lot. Yes, Dallas does have a lot of sprawl. I live close to Dallas, so that's why I picked it. – adamdesign May 4 '17 at 3:33
• @adamdesign we must be neighbors. – JDługosz May 4 '17 at 4:55
• “un-fancy”: We have similar tastes in websites too! – JDługosz May 4 '17 at 4:58
• @kingledion it's so fitting that municipios are given Roman Numerals. – JDługosz May 4 '17 at 5:00
• How can a population density of 837 per km^2 be denser than 928 per km^2? Similarly, how can 811/km^2 be a denser population than 837/km^2? – a CVn May 4 '17 at 12:20

There's been a few examples of planned cities coming up out of nowhere. Assuming you have all the resources you need

The current capital of Myanmar took 10 years to build from nothing

Brasilia took 48 months to build

So the city core is easy. The hard part is convincing people to move. If you had enough support, you could build 'close enough' to a major urban center to attract business and jobs away from it, but many newly rich nations like china often have entire towns or cities that are empty.

So the process of building a community is somewhat tricky. You need to start with attracting business and jobs, and then people. But if you had the right backing, you could certainly get a metropolis up in under a decade.

• Great advice. I had no idea about those cities in China! That's craziness... – adamdesign May 4 '17 at 3:37
• For even more fun this is a more recent article that says the city is "full". Because they moved the border of the city. forbes.com/sites/laurelmoglen/2017/03/30/… – Journeyman Geek May 4 '17 at 3:39
• And the problem is what's paying to maintain all those empty buildings while you convince/bribe people to move there? – CaM May 4 '17 at 15:37
• Infrastructure is oddly the easier part of this - but short of forcing people to move, making an attractive proposition of a greenfield city is... hard – Journeyman Geek May 6 '17 at 2:32