Major US routes vs. major Interstate routes.

[sparker]

^^^^^^^^^^^^
It's likely that since the US route system originated in the '20's and '30's, and wasn't even (almost) fully paved until after WWII, the rationale for "oddball" composite routes such as US 41 was simply for navigational purposes -- connecting areas where (a) people lived and (b) wanted to go for recreational purposes (remember, this was for the most part during the Depression and before air travel became commonplace).  For most of the U.S. east of the Mississippi River, (b) meant Florida.  So US 41 simply functioned as a normal "grid" route until it hit the KY/TN state line, then struck off in a southeasterly direction, collecting traffic from Nashville and Atlanta along the way, and (originally) winding up in Naples, FL before subsuming original US 94 and shunting across the Everglades to Miami (Beach).  Windy, rainy/snowy Chicago to sunny Miami -- that was obviously the brief.  Curiously, US 43 essentially follows the trajectory of the N-S main portion of US 41; if not for the desire for a singly-signed Chicago-to-Florida corridor, US 41 might well have joined US 31 and US 45 with a Mobile southern terminus.  Instead it ended up being celebrated in Allman Brothers lyrics as the N-S backbone of GA!

[SkyPesos]

^ probably the same case as US 66 then; relatively straight E-W from LA to OKC, then goes northeast to Tulsa, St Louis and Chicago.

[sparker]

^ probably the same case as US 66 then; relatively straight E-W from LA to OKC, then goes northeast to Tulsa, St Louis and Chicago.

Same difference, but with Bobby Troup music & lyrics!   

[gr8daynegb]

I just feel old remembering when US 10 went to Washington, US 27 into Michigan, and US 141 went to Milwaukee(and when I-43 was Wis 15 by Beloit)

I also wore an onion on my belt, which was a style at the time.......

[hbelkins]

^^^^^^^^^^^^
It's likely that since the US route system originated in the '20's and '30's, and wasn't even (almost) fully paved until after WWII, the rationale for "oddball" composite routes such as US 41 was simply for navigational purposes -- connecting areas where (a) people lived and (b) wanted to go for recreational purposes (remember, this was for the most part during the Depression and before air travel became commonplace).  For most of the U.S. east of the Mississippi River, (b) meant Florida.  So US 41 simply functioned as a normal "grid" route until it hit the KY/TN state line, then struck off in a southeasterly direction, collecting traffic from Nashville and Atlanta along the way, and (originally) winding up in Naples, FL before subsuming original US 94 and shunting across the Everglades to Miami (Beach).  Windy, rainy/snowy Chicago to sunny Miami -- that was obviously the brief.  Curiously, US 43 essentially follows the trajectory of the N-S main portion of US 41; if not for the desire for a singly-signed Chicago-to-Florida corridor, US 41 might well have joined US 31 and US 45 with a Mobile southern terminus.  Instead it ended up being celebrated in Allman Brothers lyrics as the N-S backbone of GA!

I remember when I-75 ended at the Tampa/St. Pete metro, and what is now I-275 was I-75. Was the extension southward and then across the existing Alligator Alley to Miami always planned, or a later addition to the interstate system?

[Dirt Roads]

I remember when I-75 ended at the Tampa/St. Pete metro, and what is now I-275 was I-75. Was the extension southward and then across the existing Alligator Alley to Miami always planned, or a later addition to the interstate system?

I was living in Jacksonville (Florida, of course) when construction on Alligator Alley ramped up.  Having relatives down there, I was always under the impression that I-75 down to Naples was planned earlier than the Miami extension.  (After all, there was already a similar length route between Tampa and Miami using I-4 and the Turnpike).  However, everything that I've ever seen looks like the original plan for the I-75 extension in the mid-1960s was heading for Miami.

[Avalanchez71]

And such a waste that was.  There is really not that much traffic going from Miami heading to Tampa that way that wasn't already well covered by existing highways.

[hotdogPi]

And such a waste that was.  There is really not that much traffic going from Miami heading to Tampa that way that wasn't already well covered by existing highways.

Sarasota, North Port, Port Charlotte, Cape Coral, Fort Myers, Lehigh Acres...

[SkyPesos]

And such a waste that was.  There is really not that much traffic going from Miami heading to Tampa that way that wasn't already well covered by existing highways.

that doesn't include the tourists btw

[CtrlAltDel]

And such a waste that was.  There is really not that much traffic going from Miami heading to Tampa that way that wasn't already well covered by existing highways.

I don't know about that. The AADT of I-75 through the Everglades is about 26,000, which seems a bit much for the two-lane US-41.

[sparker]

^^^^^^^^^^^^
It's likely that since the US route system originated in the '20's and '30's, and wasn't even (almost) fully paved until after WWII, the rationale for "oddball" composite routes such as US 41 was simply for navigational purposes -- connecting areas where (a) people lived and (b) wanted to go for recreational purposes (remember, this was for the most part during the Depression and before air travel became commonplace).  For most of the U.S. east of the Mississippi River, (b) meant Florida.  So US 41 simply functioned as a normal "grid" route until it hit the KY/TN state line, then struck off in a southeasterly direction, collecting traffic from Nashville and Atlanta along the way, and (originally) winding up in Naples, FL before subsuming original US 94 and shunting across the Everglades to Miami (Beach).  Windy, rainy/snowy Chicago to sunny Miami -- that was obviously the brief.  Curiously, US 43 essentially follows the trajectory of the N-S main portion of US 41; if not for the desire for a singly-signed Chicago-to-Florida corridor, US 41 might well have joined US 31 and US 45 with a Mobile southern terminus.  Instead it ended up being celebrated in Allman Brothers lyrics as the N-S backbone of GA!

I remember when I-75 ended at the Tampa/St. Pete metro, and what is now I-275 was I-75. Was the extension southward and then across the existing Alligator Alley to Miami always planned, or a later addition to the interstate system?

I-75 south of Tampa/St. Pete was one of the corridors included in the 1968 1500-mile batch of chargeable route additions.  Originally 4500 miles or new routes, defense policy events of early 1968 caused the legislation to be pared down by two-thirds; the Florida extension was one of the survivors.