What a fascinating map. On my way to Corpus Christie a few years ago I passed by the terminus for I-20 in “Kent” TX. I thought what an ignominious end it was for a 0/5 interstate as there is literally no there there.
Curious about Kent, I wikied it and, boy was I right.
As of 2005, its population was estimated at 60 residents, with three small businesses, a general store, a service station, and a post office, as well as ruins of a public school and other businesses that flourished until the 1960s. As of 2014, only the general store remained in operation; the nearest service station is in Plateau, 18 mi west along the interstate. It, therefore, has had no medical, pharmaceutical, public educational, legal, police, fire, or other governmental services beyond the post office within its boundaries; the nearest source of these is in Van Horn, 37 mi west. No motels, hotels, or trailer/RV parks, restaurants, or other tourist services are available, either.
Mostly, they’re latecomers to the system, which means they are frequently short-haul routes connecting relatively close cities: I-27, for instance, connects Lubbock and Amarillo, Texas, a distance of about 125 miles. I-14, just twenty-five miles long between Copperas Cove and Belton, Texas, was created in 2015; there are plans to eventually extend it east to Georgia.
Some of the latecomers, however, are fairly long. I-29, for example, runs from Kansas City to the Canadian border, roughly 750 miles (it’s “late” only in the sense that it was added a year or two after the original 1957 plan for the interstate). In the 1960s, locals began lobbying for a southward expansion of I-29 down to the New Orleans area, but the existing rules for numbering interstates (numbers increase west to east) prevented this because I-35 and I-45 are to the west of the proposed route, so I-49 was chosen. A section in Louisiana was built in the early 1980s; the Missouri section was largely completed in 2012 with the remainder scheduled to be done in 2022, and Arkansas still has multiple unconnected segments, with design completed but no funding for construction of the remainder.
If we follow the OP’s instruction to include only “primary” interstates (1 or 2 digits) then DC only has the two: 66 which terminates just after crossing into the District, and 95 which does not actually enter DC boundaries. Since it forms part of the Beltway, though, I consider that as serving DC.
270 terminates at the Beltway and would count, except it’s 3 digit. Similary 295, 395, 495 (which IS the Beltway) and 696.
If you further narrow it down to those major interstates divisible by 5 - e.g. 5, 10, 15 etc. - how many cities have 2 or more of those?
I’d expect a fair number of places to have two of those (a N-S “5” intersecting an E-W “0”), but not many with more than two, as the nature of the “major” interstates is that they’re usually somewhat spread out.
However, Toledo appears to have 3, due to the fact that I-80 and I-90 share a roadway through parts of Indiana and Ohio. I-75 runs through Toledo, and I-80/I-90 run along the city’s southern border.
I’m inclined to agree, since the one time I drove to Milwaukee I took that route to deliberately avoid the Chicago area and I didn’t see any sign of a nearby metropolis on those roads before I got to the Milwaukee suburbs.
As previously mentioned, Atlanta also has three major interstates: I-20, I-75, and I-85. 75 and 85 share an alignment through downtown Atlanta (the “Downtown Connector”), so it’s the same situation as Toledo.
Thanks to the graphic that @Mr_Downtown shared, I can see (and have confirmed on Google Maps) that Dallas has four major interstates within its city limits: I-20, I-30, I-35E, and I-40. Fort Worth has three: I-20, I-30, and I-35W.
Since someone will want to know (as did I), the largest city to not be served by an Interstate is Fresno, California. (9 of the 10 largest cities to not have an Interstate are in CA; the other is (arguably) Anchorage, Alaska. The “arguably” part is because Alaska has its own “interstate” system, numbered A1 through A4, that is paid for by the state. The signage, however, is identical to that of the Eisenhower Interstate System.)
H-2 in Hawaii (which is indeed part of the Interstate Highway System), is 8.33 miles long. Given that its naming convention is different (beginning with H), I’m not sure if this would be considered a “primary” highway.
As Qadgop mentioned, Baltimore has I-95 going through it and I-70 ending exactly at the city limit (by the time it was time to start building inside Baltimore City, people had sort of woken up to the whole “wait, exactly why are we wiping out entire parts of the city to put a road through?” and the whole thing was delayed long enough to give up on it. Some of what would have been the intown end exists as a freeway segment if US 40). Los Angeles has 10 and 5 and if you reeeaaalllyyyyy stretch it some may count 15. Sacramento has 80 and 5, Seattle 90 and 5. Durham NC has 85 and 40.