# Why no Interstate I-30, I-50 and I-60? **URL:** \ **Category:** Factual Questions\ **Created:** [December 17, 2015, 3:10am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660 "2015-12-17T03:10:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [December 17, 2015, 3:10am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/1 "2015-12-17T03:10:05Z")
I was looking at a map of the US that had on it the Interstate Highway System. I happen to be looking at East-West Interstates that cross most, if not all of the US. For example, you can jump on Interstate 80 in San Francisco, CA and drive all the way to Teaneck, NJ, which is a little over 2,900 miles. As I was looking at the map I noticed something. If you start in North Dakota, and work your way south to Texas you find a number of E/W Interstates that span the country; I-90, I-80, I-70, I-40, and I-10. What you don’t find is I-60, I-50, I-30 and I-20? Were they ever planned, or is the numbering systems the way it is for a specific reason? Okay, there is an I-20, but it starts in West Texas and heads east from there. ---
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [December 17, 2015, 3:28am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/2 "2015-12-17T03:28:29Z")
> [@](#): > > There is no I-50 or I-60 (though North Carolina has proposed an I-50), as routes with those numbers would likely pass through states that currently have U.S. Highways with the same numbers, which is not normally allowed under highway administration guidelines. > **[Interstate Highway System](https://en.wikipedia.org/wiki/Interstate_Highway_System)** > > The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, or the Eisenhower Interstate System, is a network of controlled-access highways that forms part of the National Highway System in the United States. The system extends throughout the contiguous United States and has routes in Hawaii, Alaska, and Puerto Rico. > In the 20th century, the United States Congress began funding roadways through the Federal Aid Road Act of 191... > [@](#): > > Interstate 30 (I-30) is an Interstate Highway in the southern United States. While most interstate routes ending in zero are major cross country routes, I-30 is a comparatively short regional route serving only two states. I-30 runs from I-20 west of Fort Worth, Texas, northeast via Dallas, Texas, and Texarkana, Texas, to I-40 in North Little Rock, Arkansas. > **[Interstate 30](https://en.wikipedia.org/wiki/Interstate_30)** > > Interstate 30 (I-30\[a\]) is a major Interstate Highway in the southern states of Texas and Arkansas in the United States. I-30 travels 366.76 miles from I-20 west of Fort Worth, Texas, northeast via Dallas, and Texarkana, Texas, to I-40 in North Little Rock, Arkansas. The highway parallels U.S. Route 67 (US 67) except for the portion west of downtown Dallas (which was once part of I-20). Between the termini, I-30 has interchanges with I-35W, I-35E, and I-45. I-30 is known as the Tom Landry Free ---
**Author:** ![Tangent](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tangent/32/3098_2.png) [@Tangent](https://boards.straightdope.com/u/Tangent)\ **Post date:** [December 17, 2015, 5:06am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/3 "2015-12-17T05:06:48Z")
Yep, I drive on I-30 and I-20 all the time. ---
**Author:** ![Mr\_Downtown](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@Mr\_Downtown](https://boards.straightdope.com/u/Mr_Downtown)\ **Post date:** [December 17, 2015, 5:15am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/4 "2015-12-17T05:15:57Z")
When AASHO developed the new Interstate numbering scheme, it wanted to avoid confusion with the existing interstate numbering system (the one we now think of as US routes). So they skipped I-50 and I-60, which could come have come uncomfortably close to (or even be multiplexed with) US 50 and US 60. Diagonals have always presented something of a problem for the integrity of the system. I-30 and I-44 were in the original scheme, but the eventual crisscrossing of I-45 and I-49 with I-69 will be a bit of a kludge. Some of the Aspergers-afflicted roadgeeks who post at [aaroads.com](http://aaroads.com) get hot and bothered by any flaws in the system. Pennsylvania’s out-of-sequence I-99 makes them chew their tongues. ---
**Author:** ![RadicalPi](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/radicalpi/32/9806_2.png) [@RadicalPi](https://boards.straightdope.com/u/RadicalPi)\ **Post date:** [December 17, 2015, 5:28am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/5 "2015-12-17T05:28:09Z")
> [@Mr\_Downtown](#): > > When AASHO developed the new Interstate numbering scheme, it wanted to avoid confusion with the existing interstate numbering system (the one we now think of as US routes). So they skipped I-50 and I-60, which could come have come uncomfortably close to (or even be multiplexed with) US 50 and US 60. Avoiding repeated numbers is also why the two systems were arranged differently. While both US routes and interstates have east-west routes as even numbers and north-south routes as odd numbers, in the US routes system, the lowest even numbers are in the north, and in the interstate system, the lowest even numbers are in the south. Similarly, I-5 is in the west, and US 5 is in the east. However, the rule that US route and interstate numbers should not repeat in a state has weakened over time. US/I-24 has been an exception in Illinois since the beginning, but now there’s US/I-41 in Wisconsin, and US/I-74 in North Carolina. Others have noted that I-20 and I-30 exist, but you are right that they are not cross-continental routes. On the north-south side of things, I-45 exists, but it is not a major route either, covering only a short distance in Texas. ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [December 17, 2015, 5:42am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/6 "2015-12-17T05:42:53Z")
> [@Mr\_Downtown](#): > > Some of the Aspergers-afflicted roadgeeks who post at [aaroads.com](http://aaroads.com) get hot and bothered by any flaws in the system. Pennsylvania’s out-of-sequence I-99 makes them chew their tongues. Same goes for [I-238:](https://en.wikipedia.org/wiki/Interstate_238) > [@Wikipedia](#): > > The number does not follow established rules for numbering Interstates, as there is no I-38. As it connects two auxiliary routes of I-80, it would normally use a three-digit number ending in 80, but of the nine possible numbers, two (180 and 480) were in use by State Routes (the latter an Interstate until 1968), and the remainder were already in use by other California auxiliary routes. (I-880 was designated at the same time as I-238.) There’s also I-82 in Washington state, which is entirely NORTH of I-84. :smack: ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [December 17, 2015, 7:30am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/7 "2015-12-17T07:30:07Z")
IIRC, if you stay on California’s I-280 South it eventually changes name to I-680 North. 🙂 ---
**Author:** ![yabob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/yabob/32/2821_2.png) [@yabob](https://boards.straightdope.com/u/yabob)\ **Post date:** [December 17, 2015, 2:39pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/8 "2015-12-17T14:39:21Z")
> [@septimus](#): > > IIRC, if you stay on California’s I-280 South it eventually changes name to I-680 North. 🙂 Basically, yes. Technically, both end at the junction with 101. And you are changing directions because you are going around the south end of the bay to proceed up the other side. Over by Berkeley you can find yourself travelling simultaneously on 80 East and 580 West while actually going north. That pesky bay again. ---
**Author:** ![Powers](https://avatars.discourse-cdn.com/v4/letter/p/edb3f5/32.png) [@Powers](https://boards.straightdope.com/u/Powers)\ **Post date:** [December 17, 2015, 3:09pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/9 "2015-12-17T15:09:19Z")
Keep in mind that the country is wider than it is tall. So there is no need to have nine east-west cross-country routes just because that’s how many two-digit multiples of 10 there are. Assuming a similar spacing as for major north-south routes, it’s inevitable that some would be skipped, or would be shorter than cross-country. Powers &8^] ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [December 17, 2015, 4:45pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/10 "2015-12-17T16:45:20Z")
> [@yabob](#): > > Over by Berkeley you can find yourself travelling simultaneously on 80 East and 580 West while actually going north. That pesky bay again. The proposed Interstate 270 in Illinois had to be renamed when everyone realized that the beltway would actually intersect with itself, leading to the junction of I-270 and I-270. The north-south leg was renamed I-255. Nowadays I-255 runs into Illinois Route 255. ---
**Author:** ![dolphinboy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dolphinboy/32/330_2.png) [@dolphinboy](https://boards.straightdope.com/u/dolphinboy)\ **Post date:** [December 17, 2015, 5:33pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/11 "2015-12-17T17:33:22Z")
A more complicated answer than I expected. Thanks for fighting my ignorance. ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [December 17, 2015, 5:46pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/12 "2015-12-17T17:46:54Z")
Interstates ending with 0 and 5 were designated as the primary cross country routes. There are only ten of each number. But it was not deemed necessary to have ten going east-west, so not all the available numbers were used. For example, there are only seven Interstates crossing the boundary between the Pacific and Mountain time zones. One of them is I-8. So not all the numbers ending with zero are used. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 17, 2015, 6:37pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/13 "2015-12-17T18:37:20Z")
> [@buddha\_david](#): > > There’s also I-82 in Washington state, which is entirely NORTH of I-84. :smack: That wasn’t originally out of numerical order. I-84 used to be I-80N (and I-80 between Salt Lake City and the Bay area was I-80S). They decided to get rid of the N/S designations and renumbered I-80N. There is no even number between 80 and 82, so they ended up with out-of-sequence numbers. What they should have done is renumber I-80S, but then they’d also have had to renumber various side freeways in the Bay Area. So they took the easier way out and renumbered I-80N. > [@jtur88](#): > > For example, there are only seven Interstates crossing the boundary between the Pacific and Mountain time zones. One of them is I-8. So not all the numbers ending with zero are used. Two others are I-84 and I-15. There’s only 4 interstates that cross the entire US from east to west: I-10, I-40, I-80, and I-90. ---
**Author:** ![cmkeller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmkeller/32/118_2.png) [@cmkeller](https://boards.straightdope.com/u/cmkeller)\ **Post date:** [December 17, 2015, 7:34pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/14 "2015-12-17T19:34:36Z")
dtilque: > [@](#): > > There’s only 4 interstates that cross the entire US from east to west: I-10, I-40, I-80, and I-90. Actually, only 3, as I-80 never gets further east than New Jersey, with New York City east of its end-point. ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [December 17, 2015, 7:40pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/15 "2015-12-17T19:40:47Z")
> [@cmkeller](#): > > Actually, only 3, as I-80 never gets further east than New Jersey, with New York City east of its end-point. If we’re gonna get _that_ nitpicky, we should also disqualify I-40 which ends in Barstow, California which is over a hundred miles inland. ---
**Author:** ![JerrySTL](https://avatars.discourse-cdn.com/v4/letter/j/e274bd/32.png) [@JerrySTL](https://boards.straightdope.com/u/JerrySTL)\ **Post date:** [December 17, 2015, 10:06pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/16 "2015-12-17T22:06:34Z")
> [@kunilou](#): > > The proposed Interstate 270 in Illinois had to be renamed when everyone realized that the beltway would actually intersect with itself, leading to the junction of I-270 and I-270. > > The north-south leg was renamed I-255. Nowadays I-255 runs into Illinois Route 255. Were would I-270 run intersect with itself? Up near Edwardsville? Why didn’t they name it all I-255 then? I’ve always found the I-255/I-270 very strange. Many other cities have just one name for such ring roads. ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [December 17, 2015, 10:27pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/17 "2015-12-17T22:27:19Z")
> [@JerrySTL](#): > > I’ve always found the I-255/I-270 very strange. Many other cities have just one name for such ring roads. I-255 is a ring road applying to traffic N/S bound from I-55, and I-270 pertains to traffic E/W bound from I-70… So it probably reduces confusion, rather than adding to it, since this conforms the rule of even numbers E/W and odd numbers N/S and the ring road is recognized as an alternate for both… ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [December 17, 2015, 11:38pm UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/18 "2015-12-17T23:38:31Z")
> [@JerrySTL](#): > > Were would I-270 run intersect with itself? Up near Edwardsville? Yes. Strictly speaking, just to the west of Glen Carbon. > [@](#): > > Why didn’t they name it all I-255 then? I-270 (the part from I-55/I-70 west across the Mississippi) was built and named first. And if they named it all I-255, then we would have ended up with the Intersection of I-255 and I-255. > [@](#): > > I’ve always found the I-255/I-270 very strange. Many other cities have just one name for such ring roads. You think that’s strange. Originally, I-270 was the part of the beltway that ran between I-55/I-70 in Illinois to the intersection with I-70 in Missouri. From I-70 to I-44, the beltway was I-244, and from I-44 to I-55 it was I-255. That turned out to be totally confusing for drivers who were trying to use it to detour around downtown St. Louis, and it finally got one continuous designation. > [@jtur88](#): > > I-255 is a ring road applying to traffic N/S bound from I-55, and I-270 pertains to traffic E/W bound from I-70… So it probably reduces confusion, rather than adding to it, since this conforms the rule of even numbers E/W and odd numbers N/S and the ring road is recognized as an alternate for both… That would be entirely logical, except that I-270 is marked N/S from I-55 to I-70, then E/W from I-70 on one end to I-55/I-70 on the other. To be fair, it does turn from N/S to E/W. ---
**Author:** ![Morbo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/morbo/32/389_2.png) [@Morbo](https://boards.straightdope.com/u/Morbo)\ **Post date:** [December 18, 2015, 12:38am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/19 "2015-12-18T00:38:07Z")
> [@JerrySTL](#): > > I’ve always found the I-255/I-270 very strange. Many other cities have just one name for such ring roads. You mean like [Loop 12](https://en.wikipedia.org/wiki/Texas_State_Highway_Loop_12) in Dallas? 🙂 > [@](#): > > Starting in the east at Interstate 30, Loop 12 goes north as Buckner Boulevard, following surface streets past White Rock Lake. Just north of White Rock Lake, it intersects Spur 244[2] and becomes Northwest Highway to the west; because there is an eastern and a western segment to this part of the road, at certain points the road signs read “East Northwest Highway.” It continues west along surface streets over Central Expressway (US 75) and the Dallas North Tollway and moves north of Bachman Lake and Dallas Love Field. > > After crossing Interstate 35E, Loop 12 moves south as a freeway, locally known as Walton Walker Boulevard, passing where Texas Stadium once sat at the interchanges with State Highways 114 and 183. The segment between I-35E (Stemmons Freeway) and Spur 408 is the only portion of Loop 12 that is freeway. It is also the only portion that leaves the Dallas city limits, as it runs through the eastern portion of Irving between where the road crosses the Elm Fork of the Trinity River (northern boundary, just north of the former site of Texas Stadium) and where it crosses the West Fork of the Trinity River (southern boundary). > > After intersecting Interstate 30 for the second time, Loop 12 continues south, joining surface streets again west of Mountain Creek Lake at Mountain Creek Parkway and Patriot Parkway (or Spur 408, which provides a southwesterly freeway link to I-20). It continues to the southeast, turning east along Ledbetter Drive, just north of Dallas Executive Airport (formerly Red Bird Airport). It continues east, crossing US 67, Interstate 35E for the second time and Interstate 45. At the intersection with US 175 and Murdock Road, Loop 12 turns north again as Buckner Boulevard all the way back to Interstate 30. The portion between Bonnie View Rd. and US 175 is also known as Great Trinity Forest Way as it passes across an undeveloped portion of the Trinity River and the Trinity River Audubon Center. ---
**Author:** ![cmkeller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cmkeller/32/118_2.png) [@cmkeller](https://boards.straightdope.com/u/cmkeller)\ **Post date:** [December 18, 2015, 1:00am UTC](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660/20 "2015-12-18T01:00:56Z")
buddha\_david: > [@](#): > > If we’re gonna get that nitpicky, we should also disqualify I-40 which ends in Barstow, California which is over a hundred miles inland. Good point. While obviously an interstate highway can’t be expected to go all the way to the shoreline, I’d think that to qualify as a true E-W cross-country route, it should end somewhere in a city or town on the Atlantic or Pacific coast. [Next page](https://boards.straightdope.com/t/why-no-interstate-i-30-i-50-and-i-60/740660.md?page=2)