I had no idea!!



Jim

Also, even numbered routes go east - west while odds go north - south.

The older US highway system is somewhat similarly arranged except that US Highway 1 is on the east coast and the numbers increase to the west (it looks like there is a Highway 101 in California) whereas the Interstate numbers are lowest on the west coast and increase to the east. Likewise, US highway numbers generally increase from north to south.

I always suspected reversing the order for the Interstates was deliberate.

There's more to it.

The 3 digit Interstates are offshoots of the 2 digit interstates that serve as "alternate" routes that take you along the other side of a major metro area.

For example, the 405 and 605 in So Cal are part of the I-5 system, taking you through the west side of LA and Orange County rather than through downtown.

Similarly, the 495 in the DC area takes you "around" the DC metro whereas the 95 takes you right through the center of it.

quote:

Also, even numbered routes go east - west while odds go north - south.

I-495, the Long Island Expressway, is an exception to this. It runs west to east.

I am not sure if there are other exceptions to this general rule.

quote:

Originally posted by Patrick-SP2022:

quote:

Also, even numbered routes go east - west while odds go north - south.

I-495, the Long Island Expressway, is an exception to this. It runs west to east.

I am not sure if there are other exceptions to this general rule.

495 is a three digit interstate, meaning it is an offshoot of the 95. The 95 still goes north and south. The offshoot doesn't necessarily always travel the same direction as the main highway, but does connect with it at some point.

Think of it as "branch 4 of I95".

I'm not so sure about those maps. I'd like to meet the guy that's driven I-60 through Kansas and I-50 through New Mexico.

quote:

Originally posted by Aeteocles:

Similarly, the 495 in the DC area takes you "around" the DC metro whereas the 95 takes you right through the center of it.

Well, not exactly. As originally planned, I-95 was supposed to run right through DC, but politicians claimed that this would unfairly affect low-income city residents, and these plans were scrapped. Subsequently, I-495 was built as a "beltway" around the city, connecting an I-95 terminus in VA (south of the city), and an I-95 terminus in MD (north of the city). After some decades, the Eastern portion of I-495 was re-designated I-95 as the "direct" North-South route so drivers didn't have to think about changing route numbers as they were driving. The stub that was the uncompleted I-95 route through the city became I-395 that peters out in the city, and there are still partially-completed sections along the N. Capital St. corridor, most of which have become storm water management sluices.

quote:

Originally posted by architect:

quote:

Originally posted by Aeteocles:

Similarly, the 495 in the DC area takes you "around" the DC metro whereas the 95 takes you right through the center of it.

Well, not exactly. As originally planned, I-95 was supposed to run right through DC, but politicians claimed that this would unfairly affect low-income city residents, and these plans were scrapped. Subsequently, I-495 was built as a "beltway" around the city, connecting an I-95 terminus in VA (south of the city), and an I-95 terminus in MD (north of the city). After some decades, the Eastern portion of I-495 was re-designated I-95 as the "direct" North-South route so drivers didn't have to think about changing route numbers as they were driving. The stub that was the uncompleted I-95 route through the city became I-395 that peters out in the city, and there are still partially-completed sections along the N. Capital St. corridor, most of which have become storm water management sluices.

I'm not really that familiar with the area, as I'm not from there. Only travelled through. But the numbering system was consistent, right? We need a beltway that connects I95 to the north and I95 to the south--so we name it a 3 digit extension, I495. They didn't make up a new North/South interstate with an odd numbering like I97 or I99 to accomplish it. The I495 indicates that it's an extension/beltway/alternate of the I95.

quote:

Originally posted by Aeteocles:

quote:

Originally posted by Patrick-SP2022:

quote:

Also, even numbered routes go east - west while odds go north - south.

I-495, the Long Island Expressway, is an exception to this. It runs west to east.

I am not sure if there are other exceptions to this general rule.

495 is a three digit interstate, meaning it is an offshoot of the 95. The 95 still goes north and south. The offshoot doesn't necessarily always travel the same direction as the main highway, but does connect with it at some point.

Think of it as "branch 4 of I95".

Like the 610 loop in Houston. It is a ring road and an alternate to I10.

And here's another obscure fact about the Interstate Highway System.

https://www.google.com/search?...ceid=chrome&ie=UTF-8

President Eisenhower conceived the Interstate System. President Eisenhower supported the Interstate System because he wanted a way of evacuating cities if the United States was attacked by an atomic bomb. Defense was the primary reason for the Interstate System.

I'm pretty sure the screengrabs from that meme are from CGP Grey's video on the Interstate system.

quote:

Originally posted by Aeteocles:

There's more to it.

The 3 digit Interstates are offshoots of the 2 digit interstates that serve as "alternate" routes that take you along the other side of a major metro area.

For example, the 405 and 605 in So Cal are part of the I-5 system, taking you through the west side of LA and Orange County rather than through downtown.

Similarly, the 495 in the DC area takes you "around" the DC metro whereas the 95 takes you right through the center of it.

Adding to the 3-digit convention: If the first digit is even, as in I-495, this is a route that loops around a city.

A first digit that is odd, like I-190, indicates a spur, sort of like a spoke sticking out of a hub. Maybe a route from city center to a major airport, for example.

---

Also, the "Victor Airways" used in aviation, follow some of the same conventions as interstates, N-S are generally odd numbered, E-W are even numbered.

quote:

Originally posted by sigfreund:
The older US highway system is somewhat similarly arranged except that US Highway 1 is on the east coast and the numbers increase to the west (it looks like there is a Highway 101 in California) whereas the Interstate numbers are lowest on the west coast and increase to the east. Likewise, US highway numbers generally increase from north to south.

I always suspected reversing the order for the Interstates was deliberate.

Interestingly, there is a Highway 1 right along the coast in CA. In places it is both Highway 1 and 101, in places 101 takes a more direct route while highway 1 follows the coastline. Perhaps this is a state Highway?

ETA: That didn’t take much of a google. Highway 1 in CA is a state route, not a US Highway.

quote:

Originally posted by Flash-LB:
And here's another obscure fact about the Interstate Highway System.

https://www.google.com/search?...ceid=chrome&ie=UTF-8

President Eisenhower conceived the Interstate System. President Eisenhower supported the Interstate System because he wanted a way of evacuating cities if the United States was attacked by an atomic bomb. Defense was the primary reason for the Interstate System.

Not entirely true. Ike was impressed by the German Autobahn, which Hitler constructed to move armor + personnel quickly around the country. Similarly, Ike wanted a system of U.S. highway mass transport for numerous reasons, including military & civilian use.

quote:

President Eisenhower conceived the Interstate System. President Eisenhower supported the Interstate System because he wanted a way of evacuating cities if the United States was attacked by an atomic bomb. Defense was the primary reason for the Interstate System.

And he got the idea from his time in and studying Germany, from the Autobahn.

All Interstate highways are marked in Miles. We’ve all known the distance to signs as well as the numbered small signs every mile marker in American miles.

However, there’s only one done in Metric. I-19 from Tucson AZ to the border town of Nogales AZ is done showing Kilometers and Meters on the signage.


Also, all of the big green signs on the Interstate telling you the name of the next exit a will have a much smaller sign on the top right, this indicates the exit is a right-hand exit. Occasionally you will see the top smaller sign on the top left and that indicates a left-hand exit. This is to help you ensure you are positioned early so you have time to change lanes to the left lane. There is one near me for the exit onto Classen Blvd from I-44. And to add, this is for an exit only, not the other big signs that tell you when a highway splits off. Pretty cool, huh?

As told above, the original plan was for the Nort/South to have odd numbers and the West/East to have even numbers. There were not many Interstates in existence and planned for back in the day, so that worked well. There are now many more built, and plans to build more, that now make it difficult to follow the original planned numbering system. Many of these newer Interstates are short, but needed, and so we have to learn to understand this sort of things.

One more thing, there are some Interstates that don't seem to run N/S or E/W and use the numbering system as such. One example is I-44, which runs from St Louis through Tulsa and Oklahoma City to Wichita Falls TX. The even number I-44 indicates an E/W highway, but if you look on the big map overview the highway runs more N/S than it does E/W. Go figure.

I spent 15 years in the Trucking & Transportation business as a Driver Manager, Load Planner, Safety guy, etc, and you learn all kinds of interesting facts and trivia about our system.

OH yeah, if your planned route involves crossing the George Washington bridge (NJ into NYC), try really hard to find another route. It sucks.

Most boring Interstate drive? I-10 across Texas, it's very long at 877 miles, seems to never end, and not much to see west of San Antonio. Get on a plane.
.

quote:

Originally posted by V-Tail:

quote:

Originally posted by Aeteocles:

There's more to it.

The 3 digit Interstates are offshoots of the 2 digit interstates that serve as "alternate" routes that take you along the other side of a major metro area.

For example, the 405 and 605 in So Cal are part of the I-5 system, taking you through the west side of LA and Orange County rather than through downtown.

Similarly, the 495 in the DC area takes you "around" the DC metro whereas the 95 takes you right through the center of it.

Adding to the 3-digit convention: If the first digit is even, as in I-495, this is a route that loops around a city.

A first digit that is odd, like I-190, indicates a spur, sort of like a spoke sticking out of a hub. Maybe a route from city center to a major airport, for example.

---

Also, the "Victor Airways" used in aviation, follow some of the same conventions as interstates, N-S are generally odd numbered, E-W are even numbered.

DANG IT, LR, I thought I'd be able to drop this tidbit and you beat me to it.

95 in Maine used to number the exits in order, South to North.

At some time in the relatively recent past, they changed that so that the exits are keyed to the nearest mile marker.

The nice thing about that is that you always know how much further it is to "your" exit. I get off 95 @ 395 in Bangor. That's at Exit (mile marker) 182.

I find Interstate driving supremely boring, so it's nice to be able to glance at a mile marker and know how far it is before I can get off the damned thing.

Never really paid attention, are all Interstates set up this way?

quote:

Originally posted by Patrick-SP2022:

I-495, the Long Island Expressway, is an exception to this. It runs west to east.

I am not sure if there are other exceptions to this general rule.

Sine the LIE is generally regarded as the world's longest parking lot, highway numbering conventions don't apply!