Atlanta has three interstates running through it: 75, 20, 85, providing 6 corridors to sprawl along.
Kansas City beat is out:--it has 29, 35, 70, 49, so 8 corridors to sprawl along.
Dallas only has 5 corridors to/away from down town.
(Oh, but wait: Oklahoma City _also_ has five. And...Denver, San Antonio,
Kansas City). Houston also has six, but... I-69 doesn't go anywhere
(and shouldn't be part of the Interstate Highway System). Federally
funded sprawl, that. St. Louis also has three Interstates--44, 70 and
55. Nashville, ditto: 24,40 and 55. Indianapolis has 65,69 and 70.
Birmingham has 65, 20 and 22, but is the terminus of 22...
Louisville (65, 65, 71), pairs within Cincinnati (71, 74, 75).
Columbus, Ohio, despite the apparent spaghetti of freeways, only has two interstates. Hate to see the
condition of the roads there.
Detroit gets three: 75, 94 96.
Chicago may be the winner: 90, 88, 80, 55, 57, 65, 90.
Nothing in Florida is central enough to have more than two Interstates running through them.
Charleston, SC has (weirdly) only one: I-26; Charlotte, NC has two: 77 and 85.
Knoxville sits where 40 & 75 meet.
I wonder--if you were to make a 'block size' map, in terms of distance from the interstate, where would be most remote? Many serious contenders, but as always, Nevada wins for least connected state.
Places that shouldn't have Interstate access: Lubbock, Texas. So remote!
Pittsburgh looks...weird. The Interstates don't go through it so much as around it: 79, 70, 76, in a triangle. Downtown access relies on beltways (279 and 376). Also reminds me that western Pennsylvania is functionally part of Ohio, rather than the eastern seaboard.
Washington DC is the nexus between I-66 and I-95, but thanks to I-270, functionally has another 'leg'. (A reminder that Baltimore used to be bigger than DC).
Baltimore itself only has...83,95,97.
Buffalo just has the 90, Philly the 76 and 95. NYC the 95 and 87.
Portland has I-84 and I-5. Seattle the I-5 and the 90.
So. My hypothesis: Cities start building fixed guideway transit only when it road expansion gets expensive. The cost to adds lanes becomes marginally higher over time (as the easiest options get built out first). Places that can expand their accessible area along more 'legs' face the crunch in freeway capacity later, and tend to sprawl for longer periods of time. (When one 'leg' runs out of capacity, development proceeds along another leg). Constrained geography also helps, as it concentrates trip ends in a more transit-suitable way--rivers and steeps slopes/mountains. Rivers also help, because they add the cost of bridges to highway construction, and make fixed guideway transit a more attractive alternative. So the most sprawling places ought have lots of freeway 'legs'.
Sadly, the number of Federally funded 'beltways' biases the results--many places have number Interstates that only remotely resemble circumferential beltways.
All the transit in California can be explained by the lack of Interstates--no place has more than 6 'legs': San Diego only has I-5, and surprisingly important I-8. Sacramento has the 5 and the 80.
LA, for all the talk about all it's freeways, only has the 5,10 and 15.
But a lot of beltways. SF has (nominally) just the 80, although it has
280, 680, 880 and 580 as beltways.
8 'Legs' - Kansas City
7 Legs - Chicago
6 Legs: St. Louis, Nashville, Indianapolis, Louisville, Cincinnati, Detroit, Baltimore, Houston (sort of)
5 Legs: Oklahoma City, Denver, San Antonio, Dallas, Birmingham, DC
4 Legs: Columbus, Ohio; Tampa, Orlando, Knoxville, Pittsburgh (?), Portland, Seattle, Salt Lake.
2 Legs: Buffalo
Columbus, Ohio seems like it ought have fixed guideway transit - 2 million metro population, and only 4 legs to grow along. Seems to have managed to self-sabotage itself by having a lot of other highways: 104, 62, 40,33,23...they've got to be going broke trying to pay for all that.
