Old Kansas City?
That’s what I get for eyeballing through squinted lids at Google Maps on a browser.
The Twin Cities metro area counts for three if you cheat a little. I-35 splits into I-35W which passes through downtown Minneapolis, and I-35E which passes through downtown Saint Paul. I-94 branches form the loop around the metro while the main route passes through both downtowns.
Damn, you beat me to the shortest Interstate. I was going to nominate I-380, a short 1.7 mile spur hanging off I-280 near San Francisco.
Note that the 3-digit interstate numbers are regional local variables, and may be re-used in different parts of the country. For example, there are three Interstates I-580: One in the San Francisco Bay Area, one near Carson City and Reno, Nevada, and one in Nebraska. (ETA: It seems a bit of a misnomer that the I-580 wiki for California I-580 calls it a “spur”. It is in fact 82 miles long and it does connect I-5 with I-80. But it doesn’t stop at I-80 any more like it used to; it now continues to U. S. 101. This was only partly a new construction; mostly it was a renumbering of other already existing highways.)
There are also three Interstates I-380 and a fourth proposed.
The longest non-0/5 (I assume latecomer) primary interstate is I-94, which runs from Billings MT to Port Huron MI. I don’t know the length offhand but certainly more than 1000 miles.
The rule about increasing numbers going east and north for primary interstates is actually violated a number of places. Most of these are where two ostensibly north-south or east-west highways cross. Last time I looked, there were about half a dozen such. For example, I-89 crosses I-91 at White River Junction VT, so the sections south of there are out of sequence. There are at least two interstates that are wholly out of order: I-99 in Pennsylvania and I-82 in Washington and Oregon. I-99 is due to some powerful congrssman wanting his district served by an Interstate. I-82 is due to renumbering I-80N to I-84.
There are even a few two-digit interstates which have several unrelated segments in several different states (and don’t represent segments of a longer planned interstate, like I-69), such as I-88, which is an interstate in New York, and a completely separate interstate in Illinois.
Memphis has between 2 and 4, depending on how you count them. I-40 and I-55 definitely count. I-69 officially has about 15 miles in Memphis, but it’s not signed as such; the I-69 signs are only on the Southaven, MS side of the city/state border. A little bit further south is I-269, Memphis’s outer beltway. I-22 starts there, but in Mississippi.
Knoxville and Chattanooga both have two interstates in town with a third starting in the next county over (75, 40, 81 for Knoxville; 75, 24, 59 for Chattanooga).
And also the old US 50.
And I just gotta point out that MA Route 3 briefly travels north on 95 (and 128)
Fun fact: The entire island of Oahu, along with a few minor islands in the state, is in the City and County of Honolulu.
That’s not the only “misnomer.” I-295, aka the New Jersey Turnpike, runs 92.3 miles in three states. I-275 around Cincinnati also loops through three states and runs 83.71 miles. And the big daddy of them all is I-476, the Northeast Extension of the Pennsylvania Turnpike, which runs 129.61 miles.
I-878 in New York City, which is not signed, is only .7 miles. The shortest Interstate route which is actually signed is I-110, 0.9 miles, in El Paso
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How come nobody’s counting I-75 as a 5th highway for Dallas?
I-75 runs a few states east of Texas. Perhaps you’re thinking of US-75, which does run through Dallas?
I was actually going to start a separate thread to ask that, to avoid hijacking this one, but I see you’ve already answered it.
Of the cities that have Interstates, I wonder what the largest city served by the fewest “primary” Interstates as defined by the OP is. The San Francisco Bay Area has a crazy number of three digit Interstates, and US 101, but only one two digit Interstate – I-80. Is there any city bigger than San Francisco with only one?
Austin, TX (pop. 1.01 million, larger than San Francisco) served only by I-35.
Strictly speaking, San Jose is also more populous than SF, and not served by ANY two-digit Interstates. Several three-digits, tho.
69 goes from Fort Wayne to Indy and up to Lansing
Beloit Wisconsin population 37k or so has three I-39; I-90: and is one terminus for I-43.
Normal, Illinois population 52k is surrounded by I-55 and I-74 and is the terminus of I-39.
Champaign Illinois pop 89k has I-72, I-74; and I-57.
Birmingham, Ala has 4: 20, 22, 59, and 65.
ETA just outside Portage Wisconsin pop 10k, I39 merges with I90 and I94 for its run to the stateline.
Duh, yes. I forgot 75 (“Central Expressway”) is a U.S. highway and not an interstate, though I’d be hard-pressed to explain the difference.
Which is why rush hour lasts nearly all day (morning rush “hour” bleeding into afternoon traffic) and why the city has gotten so badly congested.
Las Vegas has I-15 that runs thru the center of the valley on a from-Los-Angeles-to-Salt-Lake-City line and they also named the new road from the new dam bypass bridge to US-95 and then on into I-15 as I-11 so technically I suppose Las Vegas has 2 Interstate Highways.
Does the US Highway system count? Or just the Interstate Highway system?
Only tangentially related to the OP, but I’d just like to share the weird fact that one stretch of freeway in the Bay Area is simultaneously 80 East and 580 West.