Will the real longest state route in the US please stand up?

[Duke87]

Wikipedia asserts that MT 200, at 706.272 miles (such precision!) is the longest state route in the US.

I... am not convinced this is accurate.

At issue is CA 1, whose official length is given as only 655.845 miles... however because CalTrans is CalTrans, this figure omits the length of CA 1's multiple concurrencies with US 101, and I suspect it may also omit the sections of route which have been relinquished from state maintenance. Regardless of the details it is clear this official number is lowballed by some substantial margin.

The TravelMapping site calculates CA 1 as being 700.8 miles long and MT 200 as being 708.92 miles long. Buut these numbers are calculated based on the site's route traces, and routes with a lot of mountainous twists and turns routinely have their lengths underestimated because the route trace typically simplifies such things to a small number of straight lines rather than tracing out all the switchbacks and whatnot. So I'm still not convinced.

I asked Google for directions following CA 1 from end to end. I had to do this segment by segment due to limited numbers of drags to modify the route available, but by this method I came out with almost 740 miles end to end for CA 1.

That number itself has some margin of error in it depending on Google's imprecision and any errors I may have made and not noticed in where I was dragging. Even if we allow for +/- 10 miles though, this still suggests CA 1 is longer than MT 200 by an amount beyond the margin of error in the measurement.

I thus am comfortable concluding that CA 1 is longer than MT 200 and is the longest state route in the US.

Anyone care to dispute? Or have any other thoughts?

[Max Rockatansky]

Considering MT 200 is one of many continuous State Routes carrying said number I'd say that the true champion is ID/MT/ND/MN 200.  Something else worth mentioning with regards to CA 1 was that it's southern segment was originally part of the first CA 3 and US 101A.  I never really understood why CA 3 wasn't just simply reapplied to it's original highway during the 1964 State Highway renumbering. 

[kphoger]

because CalTrans is CalTrans, this figure omits the length of CA 1's multiple concurrencies with US 101, and I suspect it may also omit the sections of route which have been relinquished from state maintenance.

Is it fair to say that at least the concurrencies aren't actually part of CA-1?

[Max Rockatansky]

because CalTrans is CalTrans, this figure omits the length of CA 1's multiple concurrencies with US 101, and I suspect it may also omit the sections of route which have been relinquished from state maintenance.

Is it fair to say that at least the concurrencies aren't actually part of CA-1?

Legislatively they aren't but the multiplex is often very well signed.  My personal opinion (and I say this writing a ton of articles on California State Highways) that the multiplex does count if it's actually signed in field.  Granted the Caltrans post mileage is only going to follow what is within the legislative definition of a route. 

[webny99]

NY 17 can't compete with either of the routes in the OP, but it would certainly be in the running for longest east of the Mississippi.

[thspfc]

NY 17 can't compete with either of the routes in the OP, but it would certainly be in the running for longest east of the Mississippi.

WI-35 is longer, and there's probably others.

[Flint1979]

Michigan's doesn't come close. M-28 without looking is I think about 290 miles long.

[SectorZ]

NY 17 can't compete with either of the routes in the OP, but it would certainly be in the running for longest east of the Mississippi.

WI-35 is longer, and there's probably others.

As is ME-11 at 401 miles.

[Max Rockatansky]

Speaking of the East Coast Florida has some big State Roads which are mostly hidden designations of US Routes/Interstates.  For example; FL 15 if I recall correctly is technically something like 340 miles. 

I want to say FL 5 is the longest State Road at 536.7 miles but it is almost entirely signed as US 1. 

[CNGL-Leudimin]

According to my calculations based on the major intersection tables on Wikipedia, CA 1 is actually 736 miles (1184 km) long counting its implied concurrencies with US 101 (which add 80 miles, 129 km, to its route), 30 miles (48 km) longer than MT 200.

[hotdogPi]

ID/MT/ND/MN 200 is a single route.

[Great Lakes Roads]

The longest state route in Indiana (continuous) is State Road 62, which is at 227 miles.
Now, if we are talking about the total mileage between the discontinuous sections, State Road 37 would take that title as a total distance of 229 miles in two different sections.

[jp the roadgeek]

WY/NE/IA/IL 92 is 886 miles long.

If NY 17 is truncated when I-86 is complete , NY 5 will inherit the longest moniker at 370 miles (you can add another 45 miles for PA 5).

PA 29 (Northern segment)/NY 7/VT/NH/ME 9 clocks in at 701 miles.

[NE2]

http://web.archive.org/web/20190602124339/http://www.dot.ca.gov/trafficops/exit/docs/1.pdf gives 724.98 miles. But the PMQT no longer gives the same numbers, because now it omits gaps.

[bassoon1986]

For a small-ish state, Louisiana's highway 1 is a surprising 430 miles.


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[mrcmc888]

If we want to consider overlaps, the longest state route in Tennessee is TN-1 at 539 mi, but only about 0.95 mi is signed.

[usends]

At issue is CA 1, whose official length is given as only 655.845 miles... however because CalTrans is CalTrans, this figure omits the length of CA 1's multiple concurrencies with US 101, and I suspect it may also omit the sections of route which have been relinquished from state maintenance. Regardless of the details it is clear this official number is lowballed by some substantial margin.

I'm sure your figure is closer to the truth, as I have noticed similar problems with the lengths of other routes as listed on Wikipedia.  The problem is Wiki requires every statement to be sourced, which on the one hand I do understand, but then again it's laughable to pretend every bit of DOT information is reliable.  Wiki frowns on "original research", but sometimes original research (as you have done) is the only way to get an accurate answer.

[kphoger]

ID/MT/ND/MN 200 is a single route.

According to whom?

[Flint1979]

ID/MT/ND/MN 200 is a single route.

According to whom?

Well from Idaho 200's western terminus to Minnesota 200's eastern terminus they are connected like a single route. I can see what he's saying it's supposed to be one continuous route.

[kphoger]

Well, obviously I can see what he means.  But there is no single agency over all four of those routes.  They are four routes that happen to have the same number.

[Flint1979]

Well, obviously I can see what he means.  But there is no single agency over all four of those routes.  They are four routes that happen to have the same number.

They are numbered like that as a continuation of the route imo. Michigan use to have one with Indiana and Ohio it was route 120, well now MDOT has M-120 in another part of the state but Ohio and Indiana still have their routes. It's strange that Indiana would have that number that far north but it's obviously meant as a spur of US-20.

[dlsterner]

Well, obviously I can see what he means.  But there is no single agency over all four of those routes.  They are four routes that happen to have the same number.

This:  "But there is no single agency over all four of those routes."

This is why I personally do not consider ID/MT/ND/MN 200 to be a single route.  For instance, a state in the middle (say North Dakota) could (in theory) unilaterally change the number of ND 200 to something else without input from any of the other states.  Maybe even a number already in use by a neighboring state.  If it truly were a single route, then wouldn't all four states have to agree on any changes?

Likewise, I don't consider FL 121, GA 121, SC 121 - or others that happen to maintain the same number over state lines - to be a single route for the same reason.

[Rothman]

There is no single agency over US routes, either.

[DTComposer]

because CalTrans is CalTrans, this figure omits the length of CA 1's multiple concurrencies with US 101, and I suspect it may also omit the sections of route which have been relinquished from state maintenance.

Is it fair to say that at least the concurrencies aren't actually part of CA-1?

Legislatively they aren't but the multiplex is often very well signed.  My personal opinion (and I say this writing a ton of articles on California State Highways) that the multiplex does count if it's actually signed in field.  Granted the Caltrans post mileage is only going to follow what is within the legislative definition of a route. 

That said, the longest of these concurrencies - along US-101 between Sea Cliff and Las Cruces - does not have (I'm pretty sure) a single CA-1 shield along the entire 55 miles. The LA/OC section and the Central Coast section are really two distinct routes.

From a touring standpoint I get the idea of signing as many of the coast side highways as possible as CA-1, though - they should also pick up the historic US-101 routing in San Diego County.

[US 89]

There is no single agency over US routes, either.

AASHTO sort of is, though - states aren't supposed to change US routes without AASHTO approval, unless you're Oklahoma.