Longest route you’ve seen both ends of

[kkt]

I-90 longest seen both ends
runners up:
I-80
I-5
US 101
I-84 western

[hbelkins]

Depending on how we traveled through Jacksonville during a family vacation in the early 1970s, I may have seen the southern terminus of US 23. I definitely have seen the northern terminus.

I'm thinking the longest north-south route I've definitely seen both ends of is US 25, which I have clinched. (Having been on the portion from Georgia to well into North Carolina on the same aforementioned vacation.)

[paulthemapguy]

This is an easy question for me to answer.  I-90 in Boston and Seattle.

[NWI_Irish96]

US Highway: US 12 (2483 mi)
Interstate Highway: I-10 (2640 mi)

In both cases I have actually driven on the road at one end and just crossed the road at the other end.

Indiana state highway: IN 9 (190 mi)

[Flint1979]

I-55, I-57, I-65, I-75

[BamaZeus]

I've been to both ends of I-10, but hardly anything in between

[MCRoads]

I-10 (maybe) I have been to the Jacksonville end, and I have been to LA, but not down by the beach where the actual end is.

[Rothman]

US 20, US 6, I-94, I-90, I-80, I-70, I-40, I-95...

I-85, I-91, I-89, I-87 (NY), I-81, I-93, I-59, I-65...

...I-30, I-79, I-84 (both)...

I-97

[DandyDan]

I  suppose my list is sad. Longest Interstate I have seen both ends is I-88 in Illinois. The longest US Route is US 218, but I haven't been on any of it, except for the overlap with US 34, south of Iowa City. For state route, I think it is IA 3.

[doorknob60]

US 101 (1,540 mi), and I can't even think of a remotely close second. I've been to New York City but not quite near I-80's eastern terminus. I've clinched I-84 from Portland to Ogden, UT, but not from there to Echo. I have been to San Diego but not near the Mexican border (though I have been to Canada via I-5, long ago).

[mvak36]

I-77
I-71
I-26
I-24
I-76 (Western)
I-72
I-82
I-88 (IL)

I won't do too many of 3di's but I will include the two with the longest distances
I-135
I-435 (Does a loop have an end? )

[MNHighwayMan]

I-435 (Does a loop have an end? )

Mile marker 0.

[mvak36]

I-435 (Does a loop have an end? )

Mile marker 0.

So if you go to mile marker 0, you've seen both the beginning and the end?

[bzakharin]

Probably I-476. I've been in the vicinity of both ends of I-90 (that is to say Seattle and Boston), but I've never actually seen either end

[MNHighwayMan]

I-435 (Does a loop have an end? )

Mile marker 0.

So if you go to mile marker 0, you've seen both the beginning and the end?

I mean, if we're going to assign a beginning and ending to that which doesn't have a physical beginning/ending, then using MM 0 seems to be the most logical answer. So, to answer your question, yes.

You could, however, differentiate it by going past MM 0 in both directions, with traveling clockwise being the beginning and counterclockwise the ending.

[kphoger]

I-435 (Does a loop have an end? )

Mile marker 0.

So if you go to mile marker 0, you've seen both the beginning and the end?

I mean, if we're going to assign a beginning and ending to that which doesn't have a physical beginning/ending, then using MM 0 seems to be the most logical answer. So, to answer your question, yes.

You could, however, differentiate it by going past MM 0 in both directions, with traveling clockwise being the beginning and counterclockwise the ending.

I didn't realize until now that all Interstate beltways have a point where mileage resets to zero.  I kept trying to find a counterexample (say, where the southern portion is a duplex and uses the other highway's mileage), but I can't find a single one.

[HazMatt]

I-64 and US 421 (953/941 miles)

[paulthemapguy]

This is an easy question for me to answer.  I-90 in Boston and Seattle.

Other interstates I've seen both ends of:  81, 55, 65, 71, 72, 74, 88W, 39, 41, 43, 24, 57, 12, 94, 69 (edit)
US Routes are 34, 35, 43, 64, 264 and 45.  I think thats all.

[CNGL-Leudimin]

I didn't realize until now that all Interstate beltways have a point where mileage resets to zero.  I kept trying to find a counterexample (say, where the southern portion is a duplex and uses the other highway's mileage), but I can't find a single one.

Not an Interstate, but Spanish Z-40 around Zaragoza. The Northern part of it overlaps A-2 and uses its mileage. Once it splits it counts from the start of the overlap, so it doesn't really have a kmpost 0.

[cjk374]

Clinched route: I-35

Non-clinched route: I-25

Pssst: what happened to US 61?   

[cjk374]

Interstates: 12, 30, 49 (LA & South AR), 59.

US highway:  80 (current), 171, 425 

[bdmoss88]

I-59 for me. It could almost be I-65 but we missed the north end by a few miles when we got on it off of I-94.

[TEG24601]

I-94


Runners up
I-69 (original)
I-96

[MNHighwayMan]

Clinched route: I-35

Pssst: what happened to US 61?   

I-35 is longer than US-61.

[SSOWorld]

Clinched route: I-35

Pssst: what happened to US 61?   

I-35 is longer than US-61.

US 61 was longer, until it got a haircut.