Okay, probably a dumb idea and poorly worded, but let me offer an example.
US-97 in California is a little traveled, mainly scenic highway that can be used as a rough parallel to I-5. However, once it crosses into Oregon, US-97 is much more significant. It serves an important corridor in Oregon, including cities like Klamath Falls and Bend. It even has some short freeway segments. So it goes from an insignificant highway in one state to a very significant one in an adjacent state.
Any other examples you can think of?
US 206: In PA, it is a less than 1/2 mi. connection to US 209 just across the Delaware River, while US 206 in NJ is an important arterial through northern and central NJ.
US 15: In PA, it is a limited access freeway for much of its length. In MD, it is mostly a 4 lane undivided road that is limited access with some traffic signals passing through Frederick.
US 340: In MD, it is a limited access freeway with a 65 MPH speed limit. For the 0.57 mi. section in Loudon County, VA, it is a 2 lane road with one controlled intersection (SR 671)
The trouble with this is that at a US Route can have uneven significance within a state. Here in Iowa, the parts of US 218 which are on the Avenue of the Saints are significant, being they are 4 lane divided highways, while parts which aren't on it mostly have local traffic.
US 41 in Indiana constitutes a very important highway connecting Evansville north to Terre Haute and ultimately Chicago and is used for long-haul trips across the western tier of the state. South into Kentucky it is a minor two-lane highway that is used by mainly local traffic. Of course, the Pennyrile Parkway (I-69 and I-169) serves as the four-lane alternative nearby. But that probably fits your question.
Not too far away, US 231 is again an important highway from Owensboro north to Jasper and across most of Indiana up to Lafayette. South of Owensboro, it's a minor highway that runs close to the the Natcher Parkway.
Note: I edited this post and added a lot more.
US 2 (E), 40, 60, 62, 77, 131, 136, 166, 177, 223, 400, 522: Barely enters one state, and is therefore much less important in that state. (206 was already mentioned.)
US 23, 31, 127: Freeways in Michigan, but not in the state directly to the south.
US 1: In New York, it is basically a parallel to I-95. In New Jersey, it is a major corridor itself.
US 23: While it's a freeway in both Virginia and Tennessee, I-26 "takes over" the designation in Tennessee.
US 29: Major corridor in Virginia, parallel to I-85 in North Carolina.
US 41, 45: Upper Peninsula is less important than all of Wisconsin.
US 35: Much more important in Ohio than in West Virginia (partly due to length, partly due to partial freeway status).
US 101: While it's important in every state it passes through, it is much more important in California.
US 287: No segment outside Texas can compare to Dallas-Amarillo.
One of the more extreme examples IMO:
US-52 goes from being a major four lane divided highway(and before that a freeway) in North Carolina but then immediately turns into a two lane rural road parallel to I-77 once in Virginia.
Can I say US 311? Because I want to say US 311. At least in NC it goes through a couple towns.
US 17: in Georgia it's just the surface route alternate to I-95, but in South Carolina it's the primary thoroughfare along the coast serving Charleston and Myrtle Beach.
A very extreme example: US-131. Very important in Michigan, freeway or divided highway for much of its length, yet a mere stub of less than a mile in Indiana connecting from the state line (its former end) to the Indiana Toll Road.
Quote from: 1 on October 02, 2017, 06:10:50 AM
US 23, 31, 127: Freeways in Michigan, but not in the state directly to the south.
I beg to differ on US-23 as that is a freeway or divided highway in much of Ohio.
US-31 is very important in Indiana, especially as a freeway or divided highway from Michigan south to Indianapolis.
Quote from: 1 on October 02, 2017, 06:10:50 AM
US 41, 45: Upper Peninsula is less important than all of Wisconsin.
US-45 might not be as important, but US-41 connects the major cities of the UP: Menominee, Escanaba, Marquette, and Houghton, only missing out on Iron Mountain.
Quote from: Jmiles32 on October 02, 2017, 06:29:52 AM
One of the more extreme examples IMO:
US-52 goes from being a major four lane divided highway(and before that a freeway) in North Carolina but then immediately turns into a two lane rural road parallel to I-77 once in Virginia.
Similar, though not quite the same: Much of US-48 is a four-lane expressway in West Virginia but is a two-lane road in Virginia (yes, I know it's "supposed to be" upgraded someday).
US 191 - useless in Arizona, very important in Utah
Quote from: 1 on October 02, 2017, 06:10:50 AM
US 1: In New York, it is basically a parallel to I-95. In New Jersey, it is a major corridor itself.
Along the same lines:
US 11 barely emerges from the shadows of I-81 in Maryland (and West Virginia and Virginia) whereas in Pennsylvania, the two serve very different corridors and purposes between Harrisburg and Scranton.
Quote from: jp the roadgeek on October 02, 2017, 01:52:10 AM
US 15: In PA, it is a limited access freeway for much of its length. In MD, it is mostly a 4 lane undivided road that is limited access with some traffic signals passing through Frederick.
In addition (even though we're not talking about adjacent states), I always thought it odd that US 15 was such significant route through Pennsylvania–not only a freeway for much of its length, but also a link in a greater international corridor connecting Ontario, Buffalo, and Rochester with Pennsylvania, Baltimore, Washington, and the South–whereas south of Frederick, 15 is a much less significant highway through much of Virginia and the Carolinas.
Quote from: briantroutman on October 02, 2017, 04:15:29 PM
Quote from: jp the roadgeek on October 02, 2017, 01:52:10 AM
US 15: In PA, it is a limited access freeway for much of its length. In MD, it is mostly a 4 lane undivided road that is limited access with some traffic signals passing through Frederick.
I always thought it odd that US 15 was such significant route through Pennsylvania–not only a freeway for much of its length, but also a link in a greater international corridor connecting Ontario, Buffalo, and Rochester with Pennsylvania, Baltimore, Washington, and the South–whereas south of Frederick, 15 is a much less significant highway through much of Virginia and the Carolinas.
The start of I-270 is likely what causes this. However even with that being said, I still think one could argue that south of Fredrick, US-15 is still indeed a significant route at least down into Leesburg, VA and possibly even further south to US-29 in Gainesville. It is because of NIMBYS in Virginia and probably Maryland too that US-15 remains a two lane road when in reality it should probably be at least four lanes.
US 95 in Oregon goes through empty country. All the other states with US 95 in them get a lot more on their sections of this highway!
Rick
One could mention US 6 in CA and NV; merely a shadow of its former self in CA, it serves little purpose but to provide yet another way to get from US 395 into NV (although the CA portion is on the NHS network as a STRAHNET [military emergency route/connector]). However, in NV it is a cross-state arterial -- albeit with a rather miniscule level of traffic. As a stand-alone route, it doesn't come into its own until in Utah -- and once paired with I-70, has little/no individual significance, navigation-wise, until NE Colorado. But while insignificant in CA, at least it has some utility in the states to the east.
Quote from: corco on October 02, 2017, 02:45:34 PM
US 191 - useless in Arizona, very important in Utah
Seems not real useful in Montana either, except as a northern access to Yellowstone.
US 1 is much more significant in North Carolina than it is in Virginia.
On the other hand, US 13 is much more significant in Virginia than it is in North Carolina.
US 29, while breaking away from the interstate system north of Greensboro, is still more significant in Virginia than it is in North Carolina.
US 50 is much, MUCH more significant in Maryland than it is in Virginia.
US 22 in West Virginia vs. Ohio.
Also, US 127 in Kentucky vs. Tennessee. And US 45 (and its children) in Tennessee vs. Kentucky.
US 1 in CT and RI. In CT, US 1 is a 2 or 4 lane undivided road that never strays more than a couple miles from I-95, and is a retail haven in most spots between Norwalk and Mystic. In RI, it's a separate corridor from Westerly to Warwick as I-95 stays about 15 miles inland. It is 4 lane divided for much of its length between RI 78 and RI 4, and is pretty devoid of businesses between Westerly and Narragansett.
Quote from: Quillz on October 02, 2017, 12:59:13 AM
US-97 in California is a little traveled, mainly scenic highway that can be used as a rough parallel to I-5.
I disagree. It's about as useful as it can be for a highway that's only in the state for 55 miles (discounting urban freeways and such). It's the primary connector and shortest route from most of California to most of Central and Eastern Oregon and Washington. And saying it runs parallel to I-5 is a bit misleading. Really it's a Y, where US-97 is the top right of the Y, and I-5 is the top left. Yes they run roughly parallel in Oregon, but ~100 miles apart (over a mountain range), so it's not like an I-5/CA-99 situation. And you said it's lightly traveled, but I'd estimate the CA portion of US-97 isn't significantly different than the traffic levels in Oregon,
except for between La Pine and Madras.
I guess what I'm trying to say is, just because it doesn't spend a lot of miles in CA, its connection to the longer segments in OR and WA mean it's just as important. Removing the segment, for example, would leave a big hole in the highway network and would be a pretty big problem. Another way I'm saying it is, US-97 doesn't get less important when it crosses the OR/CA border. It might be less important to California as a whole, relatively speaking, but the highway itself is the same level of importance. There's a difference.
I would argue for US-395 in Oregon though. It's more important in Nevada, being a primary arterial between Reno and Carson City (despite also being I-580 now), and the primary connector from Reno to Oregon (via CA-139, CA-44/89, or OR-31) or southern California. In California, the northern section is a bit desolate (at least north of Susanville), but the southern section serves as a fairly important link from southern CA to the Reno area. And in Washington, US-395 is a major freeway connector between Pasco and Spokane. But in Oregon, it winds through mountains, only hitting small towns like Lakeview, Burns, and John Day until hitting more civilization at I-84. And it doesn't serve much of a use for longer distance through traffic, overshadowed a lot by US-95 and US-97 (which are both faster less windy highways), and general lack of demand.
US 58 in VA vs. TN :-D