1926 US routes vs. later additions

[usends]

[CNGL-Leudimin]

Pennsylvania was right with asking for many more US Routes. Eventually many other states caught up during the 30s. However this also shows it was a mistake to place US 81 right in the middle of the county, forcing those extra long 3dus out West, some even going border to border like US 281.

[3467]

Would be interesting to see how the current ones overlap with the NHS  really the federal primary system now.Since that now includes the interstates it would show that overlap as well.
Interesting that New York and California we never that into it.
Also Illinois tried to add a lot and later would go after every bit of interstate and FAP  it could get.

[usends]

Pennsylvania was right with asking for many more US Routes.

There was certainly some difference of opinion on the desired density of the US route grid.  This contrast is most prominently illustrated along the border between Pennsylvania (which favored a dense network) and New York (which wanted only long, transcontinental routes included the system).

Eventually many other states caught up during the 30s.

Yes, the network was quickly increased such that it ended up being about as dense countrywide as it had been initially in Pennsylvania.  It could be debated whether the newer additions to the system were necessary, or whether it was more a function of "everyone wants to be on a US route".  Already by the 1930s AASHO could see where this would eventually lead, so they became more intentional about stopping the expansion.

...it was a mistake to place US 81 right in the middle of the country...

I'm not sure it was a mistake; certainly a lot of thought went into it.  During the 1920s and '30s, the country's population centroid was a little east of the Indiana/Illinois border.  I don't know if people were even calculating "population centroids" back in the 1920s, but if they were, then one could argue that US 51 should have run along that line.  Yet it was actually US 41 that was placed there, so when you look at it that way, the north-south route grid might have been skewed even further west than it should have been.  On the other hand, that may have been good foresight, because by about 1960 the centroid had moved to where US 51 is now (and of course it has continued to drift west since then, such that it's about where US 63 runs now.)

Another thing to consider is that right around the 98th meridian, annual rainfall drops off sharply, and population density along with it.  That's roughly the longitude of US 81.  I don't have the data to back this up, but I wouldn't be surprised if, back in the '20s, roughly 80% of the country's population was to the east of US 81.

...forcing those extra long 3dus out West, some even going border to border like US 281.

If long north-south routes in the West were deemed to be necessary when the system was originally implemented, then one would have expected the 2-digit north-south routes west of US 81 to go from Canada to Mexico.  Yet many of them did not, including US 83, 87, 93, 95, and 97.  Of course most of these were substantially lengthened later, and as you mentioned some 3-digit routes were added too.  But I'm still not convinced that the north-south grid was initially skewed too far east.

[Max Rockatansky]

The problem with places like California was that outside the initial run of US Routes a lot of the the state had comparatively primitive rural roadways than seen out east.  There was a handful of older Legislative Routes like LR 23 which evolved into US 395/US 6 but it wouldn't be well into the 1930s before even routed like US 66 were even signed on state maintained roads in the Mojave Desert.  Nevada interestingly seems to have been one of the earliest states out west to have developed a substantial signed highway system which is why so many early US Routes ended there rather than California or Arizona.  Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.  I don't think anyone realistically could have seen the population boom out west occurring to the degree it did back when the US Route system was created.  For the time the initial run or US Routes was pretty solid. 

[CtrlAltDel]

Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.

For the record, this is still the case. About 60% of the US population currently lives east of the Mississippi, although, as you note, it used to be much higher.

[vdeane]

Honestly, I think NY had the right idea, for the most part - the US routes should have been a backbone of major regional and national routes providing links around the country, not a motley collection of roads serving just about every corner of ever state that it became in many places (most notably PA).

[ErmineNotyours]

Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.

For the record, this is still the case. About 60% of the US population currently lives east of the Mississippi, although, as you note, it used to be much higher.

The United States center of population moved west of the Mississippi with the 1970 census.  https://en.wikipedia.org/wiki/Mean_center_of_the_United_States_population

[CtrlAltDel]

Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.

For the record, this is still the case. About 60% of the US population currently lives east of the Mississippi, although, as you note, it used to be much higher.

The United States center of population moved west of the Mississippi with the 1970 census.  https://en.wikipedia.org/wiki/Mean_center_of_the_United_States_population

Weird. If I had to guess, it probably has something to do with Alaska and Hawaii.

[GenExpwy]

Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.

For the record, this is still the case. About 60% of the US population currently lives east of the Mississippi, although, as you note, it used to be much higher.

The United States center of population moved west of the Mississippi with the 1970 census.  https://en.wikipedia.org/wiki/Mean_center_of_the_United_States_population

Weird. If I had to guess, it probably has something to do with Alaska and Hawaii.

Actually it crossed the river in the late 1970s (1980 census).

Alaska and Hawaii were states in the 1960 census. A footnote in Wiki says they moved the population center 10 miles west and 2 miles south.

[Brandon]

Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.

For the record, this is still the case. About 60% of the US population currently lives east of the Mississippi, although, as you note, it used to be much higher.

The United States center of population moved west of the Mississippi with the 1970 census.  https://en.wikipedia.org/wiki/Mean_center_of_the_United_States_population

Weird. If I had to guess, it probably has something to do with Alaska and Hawaii.

More likely California and Arizona.

[Konza]

Not to mention Florida and Texas.

[DTComposer]

For the sake of data:
-In 1900 the 19 states west of the Mississippi (Alaska, Hawaii, Arizona, New Mexico, and Oklahoma were not states yet) had just 26.5% of the total U.S. (45 states and D.C.) population.

-In 1950 (now including Arizona, New Mexico, and Oklahoma) it was at 32.0%.

-In 1960 (now including Alaska and Hawaii) it was at 33.7%.
The West grew by about 12.2 million people between 1950 and 1960; only about 850,000 of that was the addition of Alaska and Hawaii. California and Texas accounted for 7,000,000 of the growth. By comparison, the East grew by 16.3 million in this decade.

-In 1980, the West was at 37.1%.
It wasn't until the 1970s that the West gained more people numerically than the East (13.7 million vs. 9.7 million).

-In 2000, the West was at 40.5%.

-For the 2018 estimates, the West was at 42.7%.

Even though California and Texas are 1-2 in population and likely to remain so for the foreseeable future, the next 10 largest states are east of the Mississippi.

[woodpusher]

Let's not forget that the majority of the population was east of the Mississippi River in the 1920s.

For the record, this is still the case. About 60% of the US population currently lives east of the Mississippi, although, as you note, it used to be much higher.

The United States center of population moved west of the Mississippi with the 1970 census.  https://en.wikipedia.org/wiki/Mean_center_of_the_United_States_population

Weird. If I had to guess, it probably has something to do with Alaska and Hawaii.

Center of population is the point at which the map would balance if each person had equal weight.  Consequently, someone in California exerts more torque than someone in Kansas.