Evolving Urban Agglomerations of The United States

[SpawnOfVulcan]

I posted a bit of a preview in a previous thread about population density that had the graphic displaying population density in peaks and valleys across the US.

So, I've been working on this for about a month (not every day, just every now and then). Being the nerd that I am, I wanted to find a way to accurately display and identify the spatial distribution of urban agglomerations, and other urban areas, across the US.

What I ended up doing was importing US Census Tracts (2010) into ArcMap. In there, I was able to calculate population density for each tract. I fooled around with it and decided to extract all tracts with a population density of 75 people per square mile or greater. Once that was done, I began the task of identifying the urban areas. I did this by "seeding" each sizable "blob" of tracts and selecting all tracts that were contiguous to the "seed". I clicked a bunch, performing mulitple iterations, until Arc would select no more. Once that occurred, BAM!, I had my urban area. Wam bam, exported the data, and I had my urban area shapefile; from there I could get the population of each area.

Here's the map:



So, I did this for, roughly, 150 areas. I'll give you rankings for all areas with a population of 500,000 or greater (I have many many more, so if you want the population for one I don't list, just ask). Once I had my populations I set about classifying each one. Below are my classifications, which are by no means perfect; in some cases (like, 3 or 4) I had to insert bias because a few areas didn't fit entirely within the parameters of a single classification:

(some of these terms I use more loosely and assign a more broad definition to)
MR - Megaregion: contains all or part of 3 or more metropolitan areas home to 1 million or more people.
Mplx - Metroplex: contains all or part of 2 metropolitan areas home to 1 million or more people.
HUR - Highly Urbanized Region: home to 3 million or more people; has one main core.
CU - Conurbation: home to 1 million or more people; contains a majority of 2 or more metro areas home to 200,000 people or greater; has 2 or more main cores.
SCU - Smaller Conurbation: same as "Conurbation" but home to 500,000 to 999,999 people.
LUR - Larger Urban Region: home to 1 million or more people; contains all or part of a single metropolitan area with at least 1 million residents; has a single main core.
UR - Urban Region: home to 500,000 to 1 million people; contains all or part of a single, main 250,000 to 999,999 population metro area; contains a single main core.

Here are the rankings. I know it's common for many of us to get into city vs. city mode, but please realize, these numbers do not necessarily represent a metro area, or accurately identify a commuter region. These numbers represent areas with significantly (relative) consistent population density over an area. Census tracts are not perfect, so that influences these results. I've done my best to take into consideration geographical barriers (see Seattle). More isolated cities will have lower populations due to the fact that there are fewer cities nearby with which to interact and thus create development corridors between them.

1)   Northeast MR	        53,981,820

2)   Eastern Great Lakes MR     19,992,736

3)   Southern California MR	19,826,225

4)   Piedmont Atlantic MR       16,323,301

5)   Lake Michigan MR	        15,633,675

6)   South Florida MR	        14,799,569

7)   San Francisco Bay MR	7,025,429

8)   Dallas - Ft. Worth Mplx    6,300,257

9)   Houston HUR	        5,783,767

10) Seattle - Tacoma HUR	4,425,808

11) Phoenix HUR                	3,929,274

12) Central Colorado CU     	3,812,298

13) San Antonio - Austin Mplx	3,588,278

14) Sacramento HUR          	3,405,931

15) Indianapolis - L'ville Mplx 3,320,958

16) Minneapolis - St. Paul HUR	3,199,861

17) Portland CU                 2,728,909

18) St. Louis LUR	        2,691,321

19) Great Salt Lake CU       	2,205,541

20) North Alabama CU        	2,143,950

21) Southeast Louisiana CU	2,066,316

22) Rochester - Syracuse CU  	1,961,098

23) Las Vegas LUR             	1,892,824

24) Kansas City LUR           	1,805,283.

25) Central Tennessee CU    	1,734,086

26) Hampton Roads CU       	1,681,294

27) Jacksonville LUR           	1,330,906

28) Central Gulf Coast CU    	1,282,930

29) Fresno Visalia CU          	1,224,120

30) McAllen - Brownsville CU  	1,211,050

31) West Tennessee LUR     	1,185,836

32) Oklahoma City LUR      	1,142,903

33) Buffalo LUR                 1,121,944

34) Richmond LUR              	1,080,029

35) Knoxville LUR              	1,074,700

36) Tucson UR                   920,326

37) El Paso UR                  821,258

38) Chattanooga UR           	796,822

39) Tulsa UR                    788,682

40) Omaha UR                    785,736

41) Albuquerque UR           	754,454

42) Columbia, SC UR          	690,770

43) Carolina Coast SCU       	627,508

44) Little Rock UR              627,479

45) Lake Winnebago SCU    	625,728

46) Monterey Bay SCU        	622,943

47) Charleston, SC UR         	605,136

48) Tri Cities, TN SCU         	601,778

49) Boise UR                    600,305

50) Des Moines UR              	565,399

51) Spokane UR                  559,407

52) Bakersfield UR             	521,025

53) Lexington UR               	517,430

54) Reno UR                     516,110

Any comments or questions are welcome. If anyone has any input that might improve the classifications, or anything else, feel free to say so!

EDIT: I had to cut out some things in order to whittle down the data; so, sorry, no Hawaii, Alaska, Puerto Rico, etc... I also cut out water majority tracts. The colors of the areas mean nothing, they're just there to help you distinguish between them.

[ColDayMan]

We're #2! We're #2!

Sorry.

Neat map.

[SpawnOfVulcan]

Originally Posted by ColDayMan

We're #2! We're #2!

Sorry.

Neat map.

Haha, yes, y'all are. I actually have a shapefile of the density at 60 people per square mile that lumps y'all in with "Lake Michigan". Of course, it also lumps North Alabama, Chattanooga, Knoxville, etc... in with the Piedmont Atlantic. I don't think it changes the rankings much though...

I was surprised to find that there was such a divide between the Eastern Great Lakes and Lake Michigan regions; I figured that the Lansing area would have been enough to connect them.

[Leo the Dog]

Cool map!

Amazing that Southern California has crammed 20 million people in a relatively small geographical area, that will only continue to densify as there is almost no where else to sprawl.

I like how the west is still largely empty due to water. Back east anyone could settle anywhere, but the west will always be confined to huge metros.

[mthd]

interesting work!

i find it very curious though, that for example the san francisco bay area and sacramento are separate, whereas atlanta is linked all the way to raleigh through charlotte and greenville and columbia.

the experience of travelling between those places, the fact that people commute from sacramento to san francisco but not from raleigh to atlanta!, and a cursory examination of aerial photos at the same scale suggests the methodology could use some refinement...

[Derek]

Interesting that you combined Rochester with Syracuse. Rochester is slightly closer to Buffalo and more culturally connected to Buffalo than Syracuse.


I'd combine Syracuse with the Utica area, and Rochester with Buffalo.

[L41A]

This map is interesting and really illustrates the predominance of population density in the NE corridor. It also shows how in the Eastern third of the US, that there is not much uninhabited areas. It shows in the Eastern third how some of the nation's biggest metros are separated from each by smaller metro areas with smaller cities, towns, villages in between them all. It shows how the western metros are contained my mountains, desert, and government ownership of land. Interesting map but not all that surprising to me.

I appreciate your work, diligence and your sharing. You explained your methodology and kept subjectivity out of it.

[Cleveland Brown]

Originally Posted by ColDayMan

We're #2! We're #2!

Sorry.

Neat map.

And Cleveland and Pittsburgh are in the same region, but Pittsburgh has more in common with the northeast than the rustbelt

Joking aside, I think it's a fair map, even the Michigan split.

[JonathanGRR]

Originally Posted by quattordici

Haha, yes, y'all are. I actually have a shapefile of the density at 60 people per square mile that lumps y'all in with "Lake Michigan". Of course, it also lumps North Alabama, Chattanooga, Knoxville, etc... in with the Piedmont Atlantic. I don't think it changes the rankings much though...

I was surprised to find that there was such a divide between the Eastern Great Lakes and Lake Michigan regions; I figured that the Lansing area would have been enough to connect them.

I'm guessing from your map that the split is somewhere around Lowell on the west side and Grand Ledge on the east. While the drive between Grand Rapids and Lansing is pretty quick (I know of more than a few people who make the commute), it is understandable that the two areas are separate. Both metros have, for the most part, sprawled predominantly to the north and south. Between the two metros are small towns with relatively low inter-connectivity or sprawl.

If you can easily make more detailed maps, it'd be interesting to see at what points the population areas Illinois and Wisconsin connect with West Michigan...

[atlantaguy]

Originally Posted by mthd

interesting work!

i find it very curious though, that for example the san francisco bay area and sacramento are separate, whereas atlanta is linked all the way to raleigh through charlotte and greenville and columbia.

the experience of travelling between those places, the fact that people commute from sacramento to san francisco but not from raleigh to atlanta!, and a cursory examination of aerial photos at the same scale suggests the methodology could use some refinement...

I see a massive amount of river delta and open farmland west and south of Sacramento. Davis and Dixon look like tiny islands, and this obviously unpopulated area appears to run all the way south to Antioch.

It has to be more a function of geography than anything else. The lines between development and open land are much more pronounced in the West.

And of course people don't commute from Raleigh to Atlanta, unless it's on a plane.

[ozone]

I do not get the point of this map. It's basically based on census stats and a limited knowledge of regional social, economics and political relations. If you are saying that urban America is evolving into ever more complex and denser communities then I would say "no duh". The entire world is becoming more urban. It's the trajectory the human race has been on for more than 200 years.

[atlantaguy]

Originally Posted by ozone

I do not get the point of this map. It's basically based on census stats and a limited knowledge of regional social, economics and political relations. If you are saying that urban America is evolving into ever more complex and denser communities then I would say "no duh". The entire world is becoming more urban. It's the trajectory the human race has been on for more than 200 years.

He was having fun, lighten up a little.

And you would be wrong to assume the OP has a limited knowledge of regional social, economic and political relations. As I understand it this map is based on people per square mile, not commuting patterns. You said as much yourself.

[simms3_redux]

Thanks for the map (and the time it took to create), always interesting to look at this and very subjective, obviously. If you were looking for more wide-sweeping regions, I would have:

1) lumped Houston through Pensacola into one Gulf Coast region, sharing similar cuisine, I-10, oil/energy, swamps/heat, culture, etc

2) either made all of the FL Peninsula one connected megaregion, or lumped Jax in with Central FL and thrown in Ocala, too. It's an hour drive from DT Jax to Daytona and another ~45 minutes to DT Orlando without bad traffic, and between Duval and Orange counties you're talking between 1.2-1.3 million people just along 95/4, and more on the other side of the St. Johns River, which connects the two cities and defines Jacksonville and the lakes north of DT Orlando. Orlando and Miami are now culturally more similar and Jax and Tampa are culturally/historically more similar, but the 3 northern/central cities are far more connected to each other geographically and separated from SE FL...so really I'd lump the whole peninsula as one connected region (it's almost as dense as NE corridor up and down 95 and 75 and 4 going across).

3) I would have lumped Sacramento in with the Bay Area for obvious reasons

4) If you are lumping Raleigh and Atlanta in one region, well quite frankly that's a lot more unrealistic than lumping Birmingham, Chattanooga and Eastern TN (Knoxville) in with Atlanta. Not only are these cities geographically closer (Atlanta is equidistant to Birmingham, Chattanooga and Greenville, SC - 1.5-2 hours to each), it has more in common. PAM typically includes Birmingham, though not Huntsville.

5) I always got the impression that Louisville and Cincinnati were quite similar and only 1-2 hours apart...I really want to put them together but what do I know?

From Wikipedia's Article on Megaregions - the map comes from Regional Plan Association



I highly recommend the book "Megaregions" if you're interested in this stuff. Foreward by Richard Florida, our favorite, and edited by Catherine Ross who is adjunct at my undergrad alma mater, which is why I know of the book.

[atlantaguy]

^I'm a huge fan of Catherine Ross. I've been following her career for years now.

[ChiSoxRox]

Fun map, and you're more patient than I am with making such maps.

Two notes:

Is it possible to make a zoom-in of the Great Lakes group with county shape overlays? That way, it's easier to see at a glance how the splits in Michigan and Indiana align. The clump that surprises me most there is Indianapolis and Louisville joining together with that thin tendril.

Also, I wonder how long it'll be before Chattanooga and Birmingham join the Ralanta corridor. Considering how wide-spread that conurbation is, I'm impressed at the size of the split between the Piedmont and the Hampton Roads/Richmond outliers of the Northeast.

[mhays]

Integrating Canada might be more realistic. I'm biased being near the border.

[BnaBreaker]

Great map, and fantastic work. Thanks for sharing it.

I would say though, and this is really just me splitting hairs about the subjective definition of a vague term, but in my opinion I don't think the term "urban agglomeration" really fits some of these. For example, aside from the small city of Columbus, there really is a whole lot of nothing for the 100-ish miles between Indianapolis and Louisville.

[SpawnOfVulcan]

Originally Posted by mthd

interesting work!

i find it very curious though, that for example the san francisco bay area and sacramento are separate, whereas atlanta is linked all the way to raleigh through charlotte and greenville and columbia.

the experience of travelling between those places, the fact that people commute from sacramento to san francisco but not from raleigh to atlanta!, and a cursory examination of aerial photos at the same scale suggests the methodology could use some refinement...

There is quite a bit of farming going on between San Francisco and Sacramento. There was a certain amount of subjectivity in my methodology and I considered farmland to be develop able. As I said, the "research" isn't intended to identify commuter regions; if it was, San Francisco and Sacramento would be lumped together and the North Alabama region would be split into about 4 different areas.

Don't take my comments as abrasive, I'm just not good at defending methodology in a lighthearted manner.

Originally Posted by Derek

Interesting that you combined Rochester with Syracuse. Rochester is slightly closer to Buffalo and more culturally connected to Buffalo than Syracuse.


I'd combine Syracuse with the Utica area, and Rochester with Syracuse.

I would agree, but again, ArcMap was the one that identified which tracts were grouped together based on contiguity unless there was a geographical barrier that needed to be taken into consideration.

Originally Posted by L41A

I appreciate your work, diligence and your sharing. You explained your methodology and kept subjectivity out of it.

Thanx!

Originally Posted by jonathan.jam

I'm guessing from your map that the split is somewhere around Lowell on the west side and Grand Ledge on the east. While the drive between Grand Rapids and Lansing is pretty quick (I know of more than a few people who make the commute), it is understandable that the two areas are separate. Both metros have, for the most part, sprawled predominantly to the north and south. Between the two metros are small towns with relatively low inter-connectivity or sprawl.

If you can easily make more detailed maps, it'd be interesting to see at what points the population areas Illinois and Wisconsin connect with West Michigan...

I'll see what I can do. Shouldn't be difficult, all I should have to do is zoom in and export.

Originally Posted by ozone

I do not get the point of this map. It's basically based on census stats and a limited knowledge of regional social, economics and political relations. If you are saying that urban America is evolving into ever more complex and denser communities then I would say "no duh". The entire world is becoming more urban. It's the trajectory the human race has been on for more than 200 years.

It's interesting and relevant, that's the point. Just like the rest of this website and forum, it's interesting.

Originally Posted by Dralcoffin

Fun map, and you're more patient than I am with making such maps.

Two notes:

Is it possible to make a zoom-in of the Great Lakes group with county shape overlays? That way, it's easier to see at a glance how the splits in Michigan and Indiana align. The clump that surprises me most there is Indianapolis and Louisville joining together with that thin tendril.

Also, I wonder how long it'll be before Chattanooga and Birmingham join the Ralanta corridor. Considering how wide-spread that conurbation is, I'm impressed at the size the split between the Piedmont and the Hampton Roads/Richmond outliers of the Northeast.

I can do that.

As for Chattanooga and Birmingham joining that corridor... there was actually reason to consider lumping Birmingham in with Atlanta, as Talladega National Forest effectively provides a population-less barrier between the two. As for Chattanooga, it was very close, literally just a few miles.

Just to give you all an idea of the low density across the Southeast, when I brought down the density threshold to about 70 people per sq mile, Birmingham, Chattanooga, and Knoxville got lumped in with the "Piedmont Atlantic". Unfortunately, lowering that threshold also joins the "Eastern Great Lakes" to the "Northeast" megaregion; that's why I left it at 75.

[SpawnOfVulcan]

Originally Posted by BnaBreaker

Great map, and fantastic work. Thanks for sharing it.

I would say though, and this is really just me splitting hairs about the subjective definition of a vague term, but in my opinion I don't think the term "urban agglomeration" really fits some of these. For example, aside from the small city of Columbus, there really is a whole lot of nothing for the 100-ish miles between Indianapolis and Louisville.

Well, as I said in my classification definitions, some of the terms were given a more broad definition for the sake of classifications. Otherwise, I do agree with your point.

Really, urban regions in the US defy the traditional terms like "agglomeration" and "conurbation" because most of the country isn't nearly dense enough to allow those terms to be applicable. Maybe the US needs terms specific to our cities?

[SpawnOfVulcan]

Originally Posted by mhays

Integrating Canada might be more realistic. I'm biased being near the border.

Hey, I'm not familiar with Statistics Canada, so if you wanna find me the shapefiles...