Skipping the lowest spur

[Duke87]

It seems that there was some pattern with increasing spur numbers ( ie 295 in Richmond, 495 Washington and 695 in Baltimore) but in the Northeast almost every state has a 195 and 295

Of I-95's ten northeastern states (Maryland, Delaware, Pennsylvania, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, New Hampshire, Maine), five have a 195 (50%) and seven have a 295 (70%), with Pennsylvania, Connecticut, and New Hampshire having neither. Pennsylvania and New Hampshire have no x95s, Connecticut has only 395... no doubt in deference to existing CT 195 - which was CT 95 before the interstate era.

What's interesting is that while I-95 has more children than any other interstate, there is no I-995 anywhere, and of all the states it passes through only Maryland has used up every other number. I-95 passes through a lot of states, thanks to them being small in the northeast... (though it may be noted that there are eight children of I-95 in New England, 2 each of 195, 295, 395, and 495)

[hobsini2]

i think it is mainly because of the proximity to other 3dis in other states. But probably more like a "radius range" of distance from one as in the case of 470 in KC and Topeka.  Think of it like having 2 or 3 news radio stations that are broadcasting traffic reports.  Most AM stations range is roughly 70-100 miles.  Some have a bigger signal, such as 720 WGN, 780 WBBM and 670 WSCR (all in Chicago).  Those 3 i have no problem picking up at my grandmothers in central WI.  I also have no problem picking up at home 620 WTMJ in Milwaukee even though i am 107 mi from the tower.  I once picked up between Toledo and Algona, IN the Lions, Browns, Bengals, Colts, Bears, and Packers flagship stations on normal AM radio.  But i digress.

Just a thought.

[US71]

Arkansas has I-540, but no 140 or 340.  Also has 440, but no 240... maybe because Memphis has one less than 3 hours away?

To my knowledge I-340 doesn't exist anywhere.

[ftballfan]

Michigan has 275, 375, 475, and 675 off of I-75, 196, 296, 496, and 696 off of I-96, and 194 off of I-94. I have no idea why 175 was skipped, as there was not an M-175 (but M-75 still exists within 30 miles of I-75).

[Ned Weasel]

Could it be a deference to other states? At least with the even numbers- Minneapolis has 494 and 694 while Chicago has 294. Those cities are all significant to Wisconsinites and near Wisconsin.

I suspect that's the reason Kansas doesn't overlap any interstate numbers with Missouri except where it's the same interstate

What about 470?

Speaking of that, Kansas did skip 270.  Maybe it's because Colorado and Missouri already have 270, but I've long wondered whether Kansas would use 270 if the future South Lawrence Trafficway (K-10) was made into an Interstate.

[Revive 755]

Speaking of that, Kansas did skip 270.  Maybe it's because Colorado and Missouri already have 270, but I've long wondered whether Kansas would use 270 if the future South Lawrence Trafficway (K-10) was made into an Interstate.

But Kansas may have been trying to avoid duplication with US 270, which used to go further into the state.

[agentsteel53]

that leads to a good question - are there any duplicated three-digit interstate/US pairs in any state?

[xonhulu]

that leads to a good question - are there any duplicated three-digit interstate/US pairs in any state?

That should be impossible, as the same avoidance of 2 digit interstate/US pairs in the same state should prevent any duplicate 3 digit numbers as well.  But with so many later add-ons in both systems, it might be possible.  For example, if I-20 had a an I-220 loop in South Carolina and US 220 extended a little further into that state, then you'd have one example.  But I can't think of any examples that actually exist.

[NE2]

It's not just 'later add-ons' - US 830, for example, was in Washington since 1926, but US 30 has never entered the state.

[thenetwork]

In OH, the only three-digit x90 is the brief I-490 segment near downtown Cleveland.  It was mentioned before that this was originally to be named I-290 and continue as a connection to I-271 on the east side of Cleveland.  But why was it changed to I-490 is still somewhat of a mystery. 

My only theory is that since SR-2 multiplexes with I-90 on either side of Cleveland quite visibly, that adding a bona-fide 290 freeway to a freeway system that has a 90/2 or 2/90 freeway would have caused some confusion.

And then there is Buffalo's I-990, but I don't think there was much choice in what was left in available x90s either.  Nonetheless, it does give Buffalo the honor of having the highest-numbered interstate.

[Ned Weasel]

Speaking of that, Kansas did skip 270.  Maybe it's because Colorado and Missouri already have 270, but I've long wondered whether Kansas would use 270 if the future South Lawrence Trafficway (K-10) was made into an Interstate.

But Kansas may have been trying to avoid duplication with US 270, which used to go further into the state.

I completely overlooked US 270 (oops).

[mightyace]

And then there is Buffalo's I-990, but I don't think there was much choice in what was left in available x90s either.  Nonetheless, it does give Buffalo the honor of having the highest-numbered interstate.

Actually they had NO choice as all the other x90s are used up.

190, 290	Buffalo
390, 490, 590	Rochester
690	Syracuse
790	Utica
890	Schenectady

[xonhulu]

I completely overlooked US 270 (oops).

So did I, probably because it barely makes it to Kansas.  Still, that would've made a 3-digit interstate/US pair possible.

[vtk]

So why did Indiana go with 469 for Fort Wayne?  Is there an IN-269 they didn't want to duplicate?

Personally, I like the idea of vaguely reserving numbers for future highways that might be a better fit, but I don't think planners in the Interstate Era had that much foresight.

As for progressions, the idea of geographic progression of child Interstates from south/west to north/east is interesting, but I'd prefer a system where the lowest 3dI numbers are reserved for long, rural routes and higher ones for shorter urban branches.  This more or less holds true in Ohio, though I'm not sure that was the original intention, and if it was, they could have done it better.

[thenetwork]

So why did Indiana go with 469 for Fort Wayne?  Is there an IN-269 they didn't want to duplicate?

Personally, I like the idea of vaguely reserving numbers for future highways that might be a better fit, but I don't think planners in the Interstate Era had that much foresight.

As for progressions, the idea of geographic progression of child Interstates from south/west to north/east is interesting, but I'd prefer a system where the lowest 3dI numbers are reserved for long, rural routes and higher ones for shorter urban branches.  This more or less holds true in Ohio, though I'm not sure that was the original intention, and if it was, they could have done it better.

Probably because InDOT wanted to make sure that if & when I-69 was to be extended past Indianapolis, that they would have at least 3 x69 routes available for the use of future bypasses and spurs.  If they wanted to be totally safe, they should've called the Ft. Wayne bypass I-669 or I-869, since it would give south & central Indiana even more lower numbers to use and it would be extremely doubtful that there would ever be another I-x69 loop or spur north of Ft. Wayne in the Hoosier state, being so close to Michigan.

[vtk]

So why did Indiana go with 469 for Fort Wayne?  Is there an IN-269 they didn't want to duplicate?

Personally, I like the idea of vaguely reserving numbers for future highways that might be a better fit, but I don't think planners in the Interstate Era had that much foresight.

As for progressions, the idea of geographic progression of child Interstates from south/west to north/east is interesting, but I'd prefer a system where the lowest 3dI numbers are reserved for long, rural routes and higher ones for shorter urban branches.  This more or less holds true in Ohio, though I'm not sure that was the original intention, and if it was, they could have done it better.

Probably because InDOT wanted to make sure that if & when I-69 was to be extended past Indianapolis, that they would have at least 3 x69 routes available for the use of future bypasses and spurs.  If they wanted to be totally safe, they should've called the Ft. Wayne bypass I-669 or I-869, since it would give south & central Indiana even more lower numbers to use and it would be extremely doubtful that there would ever be another I-x69 loop or spur north of Ft. Wayne in the Hoosier state, being so close to Michigan.

That makes sense with the assumption that Indiana specifically wanted its 3dI families to have a geographic progression.  That certainly seems to be the case in Michigan, but I hadn't heard of any other states trying to do the same thing, and I'm not sure it's safe to assume that pattern was meant to be followed everywhere.  Some people in this thread seem to be assuming that, but as far as I'm concerned, such intention hasn't been established for any state other than Michigan.  (As for Michigan, I believe I heard of this from Chris Bessert at a roadgeek meet once, and I don't believe it was intended to represent any other states.)

[vdeane]

NY seems to do it too (more or less) but there's no reason it has to be done.  Just look at I-990.

[Michael in Philly]

NY seems to do it too (more or less) but there's no reason it has to be done.  Just look at I-990.

Well, 990 came along after the other eight x90s were neatly arranged in numerical order from Buffalo to Schenectady, didnt it?

[vdeane]

Yes, but the point is there's no rule saying that 3dis have to go in numeric order across the state.

[J N Winkler]

A related question is why some three-digit Interstates do not receive lower first digits.  Taking the example of I-35 in Kansas, why do we not have the following number assignments in lieu of what actually exists:

*  I-235 beltway around Kansas City metropolitan area (presently I-435)

*  I-435 connector between I-29 in Missouri and I-35 in Kansas (presently I-635)

*  I-635 Wichita western bypass (presently I-235)

[NE2]

Yes, but the point is there's no rule saying that 3dis have to go in numeric order across the state.

You could argue similarly that the Interstates don't form a grid because of I-99. There probably was some sort of 'rule' when numbers were assigned, at least in some states, but newly-numbered routes had to get the next available number. The same was true for three-digit U.S. Routes: 41 had, from north to south, 141 to 441, and 541 later continued the progression, but 641 went in the middle between 141 and 241.

[vtk]

Yes, but the point is there's no rule saying that 3dis have to go in numeric order across the state.

You could argue similarly that the Interstates don't form a grid because of I-99. There probably was some sort of 'rule' when numbers were assigned, at least in some states, but newly-numbered routes had to get the next available number. The same was true for three-digit U.S. Routes: 41 had, from north to south, 141 to 441, and 541 later continued the progression, but 641 went in the middle between 141 and 241.

The Interstates never really did form a strict grid.  If they did, then no two Interstates of the same parity would ever have crossed each other.  Given the existence of so many diagonal routes, it would be asinine to impose such a constraint on the system.  I-99 doesn't really break the grid any more than it was already broken. 

Read this again:

But the point is there's no rule saying that 3dis have to go in numeric order across the state.

You seem to be under the impression that this was a rule in the past, everywhere, which has necessarily been broken by new additions.  In some states, there is evidence for this, but I certainly don't believe it to be universally true.  Besides this thread, the only time I'd heard of such a progression concept was in reference to Michigan, and, now that I think about it, possibly with the 3dUS highways.  But 3dUS highways and 3dI loops & spurs are quite different in nature. 

Maybe an answer to the following question can inject some needed historical insight:  Was the numbering of 3-digit Interstates from the Yellow Book plan (original 41,000 miles) done by AASHO, or did AASHO simply approve the numbers that individual states submitted?

[NE2]

The Interstates never really did form a strict grid.  If they did, then no two Interstates of the same parity would ever have crossed each other.  Given the existence of so many diagonal routes, it would be asinine to impose such a constraint on the system.  I-99 doesn't really break the grid any more than it was already broken. 

Well, yes, but everything was at least partially in place until I-80N became I-84.

Maybe an answer to the following question can inject some needed historical insight:  Was the numbering of 3-digit Interstates from the Yellow Book plan (original 41,000 miles) done by AASHO, or did AASHO simply approve the numbers that individual states submitted?

The latter: http://cahighways.org/097-104.html#102

[english si]

Well, yes, but everything was at least partially in place until I-80N became I-84.

I-71?, I-85? I agree that removing suffixed routes messed the grid up a bit, but it was broken before that.

[NE2]

Well, yes, but everything was at least partially in place until I-80N became I-84.

I-71?, I-85? I agree that removing suffixed routes messed the grid up a bit, but it was broken before that.

Part of I-71 is between I-65 and I-75. Part of I-85 is between I-75 and I-95. Hence both are partially in place.