What's the difference between highways and freeways/the interstate in the US?

June 18, 2007 3:17 AM

What's the difference between highways and freeways/the interstate in the US?

Got curious after noticing everyone made the distinction in this question. The answers would make it seem like a highway is a road that does not require you to enter via an entry ramp, that it may have intersections or pedestrian traffic, and that it is an alternative to taking the interstate. However, where I live, I can't think of any way to get to the next major city without getting on the interstate, unless you were to drive along the frontage road, which is hardly what I would call a highway. Until reading the AskMe question, I've never heard anyone make the distinction between the interstate and the highway. Perhaps this is a regional difference? I live in a smaller city in the southwestern US along I-10 and have never driven in other parts of the country.

Also, I read the Wikipedia articles and googled around a bit, but I'm still not very clear on the distinction.

posted by pravit to travel & transportation (29 comments total)

The answers would make it seem like a highway is a road that does not require you to enter via an entry ramp, that it may have intersections or pedestrian traffic, and that it is an alternative to taking the interstate

That's exactly what it is, though with the modern interstate system in place it's just hard to imagine taking one out of state or across the country for most people. Wikipedia has a great article on the numbered highway system that should explain it for you.
posted by Roman Graves at 3:39 AM on June 18, 2007

Ok, my bad. I just noticed that you said you read the Wiki articles...but in that case, I don't understand what you're not clear about.
posted by Roman Graves at 3:41 AM on June 18, 2007

In that question, I think the main thing that forced everyone to make the distinction is the difference between limited-access roads and, um, non-limited-access roads. (General-access roads?) I could argue with that somewhat, because my hometown in the Pacific Northwest is served a state highway that's limited-access. I note, however, that its access is via stoplight at major crossroads, and by two-way stop at lesser ones, but not by ramp.

Now, in the East, there were highways for donkeys' ages before the interstate system came into being. In the Southwest, settlement didn't run so far ahead of the automobile era. There were certainly highways before the interstate&mdashsometimes by other names, such as 'the Pony Express road' early on, or 'US Route 66' later. ('You'll see Amarillo; Gallup, New Mexico; Flagstaff, Arizona; don't forget Wynona; Kingman, Barstow, San Bernardino.')

In many cases the interstates were laid out along earlier motor routes, there being no good reason to put them anywhere else. (Example: my hometown is also served by Inerstate 5, which seldom if ever runs more than two miles away from former U.S. 99.) And IIRC, in some places, the former highway is the frontage road. (Citation needed: I grovelled through several dozen Wikipedia pages on the history of U.S. highways a couple months ago, and I'm pretty sure I read it then. Can't find it now though.)
posted by eritain at 3:51 AM on June 18, 2007

s/Inerstate/Interstate/
posted by eritain at 3:53 AM on June 18, 2007

The interstates were designed to be wider and straighter than many of the old state roads. They were originally developed not just for commerce but also for defence, and their width and relative straightness was designed to allow things like missiles and large equipment to be transferred from place to place. (There's an urban legend out there that every fifth mile of the interstate had to be straight so it could act as a runway in certain circumstances. That was part of one proposal in the 30s but the idea didn't make it into the postwar era.)

The importance of the interstates to national defence allowed the federal government to give the states federal grants for their development and upkeep. This meant that the interstates in each state were roughly equivalent - with state roads, the money comes from state coffers, and there's no way to (for instance) make sure that the roads in Alabama were as well kept up as those in Georgia.
posted by watsondog at 4:40 AM on June 18, 2007

Master's in Urban Planning here. eritain has the correct answer. The West and Southwest have fewer highways and more Interstates.

Another comparison: Interstates did not begin to be built until the 1950s, by definition. Highways have been built since cars became popular, and before that, they were usually horse paths.

This site provides a simple guide to deciphering the whole numbers/letters thing, and also discusses the vernacular of "highway" vs. "interstate" etc.
posted by desjardins at 4:45 AM on June 18, 2007

eritain: Interstate 5 and California 99 are often thirty miles apart or more - 5 runs up the west, Coast Ranges side of the Central Valley, while 99 runs up the east, Sierra side. The last bits of 5 weren't built until the late 1960s. Here's a ridiculously detailed account I was reading yesterday.
posted by mdonley at 5:11 AM on June 18, 2007

If there are cross streets intersecting with the road directly (no ramps) it's not limited access.

Some use the terms freeway, expressway, and highway to distinguish between limited access, a non-limited access divided highway, and a regular two lane highway, but the usage is completely non-standard throughout the various states.

An Interstate is just one specific example of a freeway. A limited access state road or turnpike which is not signed as an Interstate can also be a freeway (and numbered as a state or US highway).
posted by wierdo at 5:38 AM on June 18, 2007

Oh, and I should have mentioned that in large swaths of the west, the reason you can't really take anything but an Interstate between cities is because the old roads are largely where the Interstate is now.

Farther east, the Interstates were usually built along new right of way, or much more so than out west.
posted by wierdo at 5:40 AM on June 18, 2007

A highway is any road that connects towns. There are highways that are limited access, and ones that aren't.

An interstate is a particular kind of highway.

A freeway or expressway is any limited-access road without a toll, whether a highway or just within a single city.
posted by ROU_Xenophobe at 5:41 AM on June 18, 2007

Since it seems the bulk of the question has been answered, I can confirm the concept is definitely regional: I grew up out west and I don't differentiate either. To me freeway, expressway, and highway are the same thing, and what other folks call highways, I'd probably call the state road or the main road, because to me they pretty much only exist where there are few roads: the mountains, etc. Or I suppose it could be an arterial road in some places, New Jersey, for instance, is a place where highways seem to be arterial roads, in my experience.
posted by dame at 5:54 AM on June 18, 2007

Interstate highways are built with a combo of federal and state money, and have to meet certain standards (no stoplights, for example).

U.S. highways existed before that (back into the 1920s at least). They *may* be divided, limited access highways built to Interstate standards in some areas, but they don't have to be. Rural U.S. highways are often two-lanes, not divided.

Each state has its own highway or transportation department, and funds its own roads as well.

How the road is signed will give you some clue as to who funded the road or highway and what standards it was supposed to be built to.

"Freeway" usually means a divided highway with limited access, but that's just colloquial. "Highway" could colloquially mean any road bigger than the one you're on: if you're on a small back road and get on U.S. 2 in northern Minnesota, you might say you were "getting on the highway" even though it's just a two-lane strip of pavement you're getting on. To the bureaucracy, I think they're all "highways" unless someone in government gave it a special name, like the Stevenson Expressway in Chicago.
posted by gimonca at 6:18 AM on June 18, 2007

I'd consider a highway something like 104 in upstate NY. Here's a satellite overheard view. Even with four lanes of traffic there are still stoplights at many intersections.
posted by yeti at 6:26 AM on June 18, 2007

mdonley, I'm guessing eritain is in Washington, where I-5 and SR (former US) 99 are generally no more than a couple of miles apart. In many places I-5 actually follows a former alignment of US 99 (though 99 had multiple routes itself over the years), so you can't drive the "old highway" without taking the Interstate.

I too grew up in the West (well, the Pacific Northwest, anyway) and have always known a distinction between highways and Interstates, though both can be "freeways." A lot of the older highways, though they technically are usually called SR (State Routes), or are US highways, are called "highway X" in informal usage: "Highway 99" or "Highway 2", for example. But one would generally not call the Interstate highway "Highway 5" -- it's invariably "I-5" to locals.

Anyway, to me a highway is an actual signed and numbered route where at least a certain level of speed is allowed. :) So here that's SRs and US Highways, usually. If it's a limited access road, that's a freeway, usually not a highway, though there is some blurriness there (SR 99 is a freeway through part of Seattle, for example -- but no one says "I'm taking the freeway there" if they are taking 99 through that part of town, they say "I'm taking 99" or "I'm taking the Viaduct").

I remember once, when I was a kid, looking at a Seattle map and noticing that Sand Point Way, an arterial a couple of blocks from my house, was a SR highway (I think it was 523, maybe? It's not a highway any more in that area. I think the old highway route now ends near Husky Stadium). I remember telling my mom "I didn't know Sand Point Way was a highway!".
posted by litlnemo at 6:36 AM on June 18, 2007

Freeway = Expressway. Always. But 'freeway' is more common usage in the west, expressway in the east (or even 'X-way'). This usage gets a little wishy-washy in places like Long Island, where you have the big lie, L.I.E., Long Island Expressway (a lie because it isn't very express much of the time) and "Parkways", which are freeways that don't allow commercial traffic. The term parkway may be used differently elsewhere. (PLEASE NOTE: In NY, people drive on parkways, and park in driveways).

Interstate is nearly always a freeway (limited access), except in special circumstances, usually temporary (temporary could be a long time, as in cases where the real freeway hasn't been built, but the existing highway still is designated by the interstate number for ease of navigation).

The old highway system was made of "US Routes", as in Route 66, or Route 2 (Secret Canadian highway running through upper Michigan /humor). It is common to find US Routes that are built as freeways (US Rouhte 23 in much of lower Michigan).
posted by Goofyy at 6:48 AM on June 18, 2007

There are a lot of overlapping terms out there meaning more or less the same thing. A freeway is a more precise technical term whereas a highway is more generic.

For the best definition of Freeway let's see what the AASHTO Policy on Geometric Design has to say.

Freeway - The highest type of arterial highway is the freeway, which is defined as an expressway with full control of access. (Basically this means that the federal or state governments have jurisdiction over the access points of the roadway for safety considerations.) Essential freeway elements include medians, grade separations at cross streets, ramp connections for entrance to and exit from the through pavements, and (in some cases) frontage roads.

From the Highway Capacity Manual, Transportation Research Board:

Highway - ...with no control or partial control of access..may have periodic interruptions to flow at signalized intersections...

So the main difference between Freeways and Highways is that of access and signalization. Interstates are generally referred to as Interstate Highways so there is some overlap. A freeway can be a highway but not vice versa. Another term is Expressway which is a type of multilane highway.

Many rural highways are 2-lane roads although they can also be multilane. Both Freeways and Highways can be under the jurisdiction of the Feds, State, or even Local governments.
posted by JJ86 at 6:54 AM on June 18, 2007

Goofyy mentioned: Freeway = Expressway. Always.

Not true. The Highway Capacity Manual calls an expressway a Multilane Highway which is most definitely not a Freeway. Even AASHTO makes a distinction between a Freeway and an Expressway.
posted by JJ86 at 7:00 AM on June 18, 2007

Does anyone know a good way to tell the difference between identically numbered highways in different states? I ask because both North Carolina and Tennessee have a State Highway 321, and the signs are exactly the same. NC 321 South is way different than TN 321 South though, as I learned once after traveling about 3 hours in the wrong direction.

Is it appropriate to pose related questions like this in a pre-existing AskMe thread if they don't warrant their own thread? If not, please accept my apologies.
posted by solipsophistocracy at 7:17 AM on June 18, 2007

solipsophistocracy, I guess you just have to know what each state's highway sign looks like. It's easy here in Washington, as it's George Washington's head on the signs. But some states have ones that don't stand out much.

Re: "expressway" -- that's definitely Eastern; so much so that I actually have no clue what one is other than that it's a highway of some kind. They don't use the term out here.

However, we do have one road that is called a "Speedway" for some reason that I do not know. Maybe it's an informal name and not official -- it's up in Mukilteo which isn't my area, so I don't know.
posted by litlnemo at 7:29 AM on June 18, 2007

Oh, I just saw that you said the signs are exactly the same. That's odd. Do they have a state abbreviation on the top or something?
posted by litlnemo at 7:30 AM on June 18, 2007

solipsophistocracy asked: Does anyone know a good way to tell the difference between identically numbered highways in different states?

US Highway routes between states have the same number for the same roadway. State Highways have different numbering systems which generally do not coincide with each other.
posted by JJ86 at 7:37 AM on June 18, 2007

I ask because both North Carolina and Tennessee have a State Highway 321, and the signs are exactly the same.

Nup, unless the people putting up the signs have gone crazy. NC 321 would have a sign with black numbers in a white diamond. TN 321 would have a sign with black numbers in a white rectangle, or white numbers in a black triangle.
posted by ROU_Xenophobe at 8:01 AM on June 18, 2007

Looking at google maps and wikipedia, 321 is a US highway, not a state highway, so the signs would be the same.
posted by cardboard at 8:08 AM on June 18, 2007

We don't particularly have the concept of "frontage road" in the Northeast. The highways connect smaller towns (of which there are a ton) and the interstates connect larger ones. Occasionally they run alongside each other, but that falls apart quite quickly.
posted by smackfu at 10:35 AM on June 18, 2007

And then there are byways.
posted by kirkaracha at 11:02 AM on June 18, 2007

Oh, man, it's a US highway? That explains why the signs are the same.

Do naming conventions for the Northbound and Southbound parts change? 321 leads west as you travel north in NC, but then curves and goes west as you travel south in TN. It's easy to get mixed up around Johnson City, TN (at the top of the curve).
posted by solipsophistocracy at 12:34 PM on June 18, 2007

It's more based on the eventual direction rather than your direction at the moment. I don't know that specific highway, but I have been on highways marked "X North" when I was going west, or whatever -- highways do wind around some, and sometimes they do it for a long time before they get back to their proper direction.
posted by litlnemo at 4:20 PM on June 18, 2007

litlnemo has sussed out my location pretty well. I have no idea why Mukilteo has a 'Speedway' either. Thanks, mdonley, for the reference. And wierdo, what do you call a highway which is grade-separated from most of the roads it crosses, but connects to some of them via stoplights? Does not the grade separation constitute a limitation of access?
posted by eritain at 7:10 AM on June 20, 2007

When a grade-separated highway changes to stoplights around here (CT), it usually has signs that say "Expressway Ends: Reduce Speed Now". So in that sense, it actually changes types at those points.

OTOH, the Sawmill Parkway does this with no warnings whatsoever (which is scary), and presumably stays a parkway.
posted by smackfu at 7:49 AM on June 20, 2007