US-81, the population dividing line

[agentsteel53]

saw this image (showing US population density) elsewhere today, and noted... damn, the population totally stops at US-81.

how did that come about?  why that road?  why not 59?  or 83?  kinda astonishing to see it illustrated like that.

[corco]

Very interesting- I always considered 83 to be the east/west divide of the country. That's roughly where humidity seems to begin and the ag lands get better.

I guess maybe the farmland doesn't really get better until 81- that'd be my explanation.

[briantroutman]

Compare that map with this one, and I think you'll see some correlation.



Up until the middle part of the last century, people were still fairly dependent upon the food supply available regionally. We now transport food more quickly and have more advanced and cost-effective irrigation, but to a large extent, the settlement patterns of the last two centuries can still be seen.

And beyond the lack of water, the topography of Rockies makes the western half of the country fairly unfit for widespread settlement anyway. Except for narrow and dense pockets like Denver, Phoenix, Los Angeles, San Francisco, etc., the West is still mostly unsettled.

[agentsteel53]

Compare that map with this one, and I think you'll see some correlation.

I tip my hat to you.  this is excellent.

one question - why the divergence north of approximately Omaha?  the rain equipotential line runs NNE-SSW, while the population line seems to be due north-south.

also, is that Bismarck I see almost as populous as Cheyenne?  I'd never have thunk it.  that Bakken oil field is really attracting people.

[agentsteel53]

Very interesting- I always considered 83 to be the east/west divide of the country.

I'll admit, I came into this discussion with a long-held belief that every time I cross US81, I have changed from east to west, or the other way around.  so I was looking for a US81 correlation, and damn if I didn't find it!

[agentsteel53]

I wonder what California looked like in Spanish colonial times, before massive amounts of irrigation.  how the Hell did anyone decide that that - with its extremely dry central valley - was a place to live!?

[J N Winkler]

one question - why the divergence north of approximately Omaha?  the rain equipotential line runs NNE-SSW, while the population line seems to be due north-south.

There is a transition to a different Köppen climate zone at the Nebraska/Kansas state line, with regions north of this line tending to be snowy and cold.  Probably a greater proportion of the annual precipitation falls as snow ("poor man's fertilizer"), which offsets the lower precipitation to an extent.

[briantroutman]

one question - why the divergence north of approximately Omaha?  the rain equipotential line runs NNE-SSW, while the population line seems to be due north-south.

There is a transition to a different Köppen climate zone at the Nebraska/Kansas state line, with regions north of this line tending to be snowy and cold.  Probably a greater proportion of the annual precipitation falls as snow ("poor man's fertilizer"), which offsets the lower precipitation to an extent.

In short, the missing piece appears to be Minnesota. In addition to the climate issue J N Winkler mentioned, I think another contributing factor may have been the presence of the Mississippi River in Minneapolis and the adjacency of Lake Superior in Duluth–having great importance for transportation. So perhaps it was the right combination of having enough precip and groundwater for crops in addition to healthy lumber supplies and iron ore deposits and navigable waterways to ship it all efficiently.

I wonder what California looked like in Spanish colonial times, before massive amounts of irrigation.  how the Hell did anyone decide that that - with its extremely dry central valley - was a place to live!?

In an era when what I'm saving for a tiny condo would have bought the entirety of Marin County...

[Brandon]

saw this image (showing US population density) elsewhere today, and noted... damn, the population totally stops at US-81.

how did that come about?  why that road?  why not 59?  or 83?  kinda astonishing to see it illustrated like that.

Historically, it was the 100th Meridian, which, as coincidence would have it, is approximately US-81.  As Brian Troutman showed, it's where precipitation drops off.  East of that line are farms depending on rain, west of that line are ranches and irrigated farms.  Take a look at the aerials on Google Maps or Bing Maps.  You'll see the change between the two types of agriculture.

[Brian556]

This map is awesome. US 81 passed through Ft Worth Tx before it was truncated. Ft Worth was always touted as "Where the west begins".
When you travel west out of Ft Worth, the land immediately becomes semi-arid, with grassless patches and cacti.

In Denton County, I-35E is heavily treed , while I-35W is open prairie. When I worked for TxDOT, we always had problems with the wind turning the signs on I-35W, but not I-35E. We figured that this was due to the lack of trees (and buildings somewhat) to damped the wind.

[bugo]

This map is awesome. US 81 passed through Ft Worth Tx before it was truncated. Ft Worth was always touted as "Where the west begins".
When you travel west out of Ft Worth, the land immediately becomes semi-arid, with grassless patches and cacti.

Fuck truncation.  It still ends at Laredo.

[Pete from Boston]

I wonder what California looked like in Spanish colonial times, before massive amounts of irrigation.  how the Hell did anyone decide that that - with its extremely dry central valley - was a place to live!?

Many people ask that question, a lot of whom actually live in California and rely on that water.

There is a good book titled Cadillac Desert, by Mark Reisner, that discusses the deals that brought water infrastructure to California and much of the West.  The book is not sympathetic, but in light of common-sense questions like yours, it's not hard to see why. 

[Brian556]

Fuck truncation.  It still ends at Laredo.

You're in denial...It's so bad to you, you want to pretend it didn't happen.

[hobsini2]

Topography I would guess also has to be a factor in pop density too. Look at the Appalachians and you can see "sparse" areas too.

[agentsteel53]

This map is awesome. US 81 passed through Ft Worth Tx before it was truncated. Ft Worth was always touted as "Where the west begins".
When you travel west out of Ft Worth, the land immediately becomes semi-arid, with grassless patches and cacti.

Fuck truncation.  It still ends at Laredo.

yeah, if I cross I-35 south of the truncation, I consider it the same thing: having crossed Old US-81.

but then again I refer to extinct highways as though they were still signed: for example, I refer to the whole thing as US-99, including the various SR-99s and all the other segments as well.  I was in Bellingham a couple weeks ago and had to translate "turn right on 99" for someone to the current name, Holly Street.

[agentsteel53]

Many people ask that question, a lot of whom actually live in California and rely on that water.

There is a good book titled Cadillac Desert, by Mark Reisner, that discusses the deals that brought water infrastructure to California and much of the West.  The book is not sympathetic, but in light of common-sense questions like yours, it's not hard to see why.

I will have to find this book; sounds like a very interesting read!

[kkt]

I wonder what California looked like in Spanish colonial times, before massive amounts of irrigation.  how the Hell did anyone decide that that - with its extremely dry central valley - was a place to live!?

For what California was like in colonial times, read Two Years Before the Mast, by Richard Henry Dana.  Briefly, the economy was all about hides -- the Spanish ranchers grew cattle, not for the meat which didn't keep long enough to be exported, but for the hides.

Some agriculture in the Central Valley started even before large-scale irrigation.  Where the cities are along CA-99 is where there was at least a little bit of water coming into the valley from rivers in the mountains.

[txstateends]

Many people ask that question, a lot of whom actually live in California and rely on that water.

There is a good book titled Cadillac Desert, by Mark Reisner, that discusses the deals that brought water infrastructure to California and much of the West.  The book is not sympathetic, but in light of common-sense questions like yours, it's not hard to see why.

I will have to find this book; sounds like a very interesting read!

A few years ago, the PBS documentary "Inventing L.A.: the Chandlers and their Times" did bring up a little about the irrigation and other movements made to try to bring more people to southern California.  IINM, I think it's still available to watch online at PBS' website.

[usends]

saw this image (showing US population density) elsewhere today, and noted... damn, the population totally stops at US-81.

how did that come about?  why that road?  why not 59?  or 83?  kinda astonishing to see it illustrated like that.

Where did you see the map?  What do the colors represent?  Races?

[Brandon]

saw this image (showing US population density) elsewhere today, and noted... damn, the population totally stops at US-81.

how did that come about?  why that road?  why not 59?  or 83?  kinda astonishing to see it illustrated like that.

Where did you see the map?  What do the colors represent?  Races?

Population density.  No color is the least dense, followed by blue, green, and up to red and yellow.

[Henry]

In terms of Interstates, I-35 would be the dividing line here.

[usends]

In terms of Interstates, I-35 would be the dividing line here.

Only up to Kansas City.  North of there, I'd say I-29.

[usends]

Where did you see the map?  What do the colors represent?  Races?

Population density.  No color is the least dense, followed by blue, green, and up to red and yellow.

I'd say population density is represented by dot density.  The colors are another variable.

[NE2]

It is colored by race, with whites replaced by Smurfs. It doesn't seem to be loading, but: http://www.coopercenter.org/demographics/Racial-Dot-Map