Measuring distance to and between cities

[golden eagle]

When you see a mileage sign that says, for example, "Memphis 85", is that the distance from that point to the Memphis city limits or is it to another designated point in Memphis? Most maps that I've seen with a distance chart between cities have indicated that the distance is from a central point between the cities (perhaps, downtown).

[agentsteel53]

it tends to be the center of town.  Here in San Diego there are signs that say "San Diego 12" while being within city limits.

[Bickendan]

It's either the center point of the city or to the city hall.

The distance to Portland is two miles more than the mileposts on I-84 east of I-205.
Pop quiz: Why?

[agentsteel53]

The distance to Portland is two miles more than the mileposts on I-84 east of I-205.
Pop quiz: Why?

unfinished freeway that would've reduced the distance by two miles?

[TheStranger]

It's either the center point of the city or to the city hall.

The distance to Portland is two miles more than the mileposts on I-84 east of I-205.
Pop quiz: Why?

The I-80N alignment along US 26 not being constructed?

[J N Winkler]

it tends to be the center of town.  Here in San Diego there are signs that say "San Diego 12" while being within city limits.

This is not uniform across the US and does not apply in Kansas.  For example, there is a sign reading "WICHITA 2" in Haysville, Kansas--the distance given is to the south Wichita city limit (along US 81) rather than to the center of Wichita, which is considerably further.

My personal preference is to have all distances referred to a designated zero point for each signed destination, but "ordinary" motorists (i.e., not-mathematically-minded non-road-enthusiasts) generally want to know how far they have to go before they are in a city, and often state DOTs choose to accommodate that wish.

[TheStranger]

This is not uniform across the US and does not apply in Kansas.  For example, there is a sign reading "WICHITA 2" in Haysville, Kansas--the distance given is to the south Wichita city limit (along US 81) rather than to the center of Wichita, which is considerably further.

My personal preference is to have all distances referred to a designated zero point for each signed destination, but "ordinary" motorists (i.e., not-mathematically-minded non-road-enthusiasts) generally want to know how far they have to go before they are in a city, and often state DOTs choose to accommodate that wish.

I tend to be one who likes the "outer city limit" as the target distance more - though I can see an argument against that for a massive municipal territory like Los Angeles or San Diego - simply because entering a normal-sized city should be enough to know you're "there" and that it's time for the traveler to focus on finding his or her individual exit.

i.e. on I-80 westbound at Exit 26 in the East Bay, San Francisco is marked on a distance sign as being 27 miles away (Pinole is the other destination on that sign, as 6 miles out).  I bet you most people consider themselves "in" San Francisco as soon as they encounter the closer Exit 2C (Fremont Street) though, at the foot of the Bay Bridge.

Out here, I can be at least 2-3 miles away from the outer city limit of Sacramento, and still see signs for "US 50 West - Sacramento" pointing to onramps - which I find counterproductive, as the city isn't large enough to really have regions within town that aren't considered "part" of Sacramento.  (On the other hand, Los Angeles districts fit this well - Hollywood, etc.)

[huskeroadgeek]

I think measuring distance to the center of the city makes the most sense, because it's a consistent point that can be agreed upon that has significance as a destination. The outer city limit of a city many times is nothing more than an imaginary line that has no significance as an actual destination to measure to. Besides once you get near a larger city and the exits get more numerous, whether you're actually inside the city limits of the main city or not, the distance to upcoming exits is usually what appears on distance signs. If the distance to the center of the city is noted it is usually noted as "Downtown" or something like that.

[Bickendan]

It's either the center point of the city or to the city hall.

The distance to Portland is two miles more than the mileposts on I-84 east of I-205.
Pop quiz: Why?

The I-80N alignment along US 26 not being constructed?

Yep.

[TheStranger]

I think measuring distance to the center of the city makes the most sense, because it's a consistent point that can be agreed upon that has significance as a destination. The outer city limit of a city many times is nothing more than an imaginary line that has no significance as an actual destination to measure to. Besides once you get near a larger city and the exits get more numerous, whether you're actually inside the city limits of the main city or not, the distance to upcoming exits is usually what appears on distance signs. If the distance to the center of the city is noted it is usually noted as "Downtown" or something like that.

It really is dependent on city size though - with San Francisco, it's small enough (only 7 x 7 miles or so, approximately) that reaching the city limits would absolutely be the measuring point, particularly coming in from the northeast.

One way I've always felt that would make this work is to note, within a 15 mile radius, that the distance being referred to is for the control city's downtown.

[agentsteel53]

My personal preference is to have all distances referred to a designated zero point for each signed destination, but "ordinary" motorists (i.e., not-mathematically-minded non-road-enthusiasts) generally want to know how far they have to go before they are in a city, and often state DOTs choose to accommodate that wish.

what is the point of knowing that you are "in the city"?  a lot of the time, you have crossed an arbitrary line, and unless you are a zoning-ordinance geek, you will never know the difference between the houses and Walmarts of the outskirts of a city, versus the houses and Walmarts of the closest suburb.

to me, knowing the distance to the downtown is universally more useful.  if I see a sign saying "San Diego City Limits" and - just past it - one that says "San Diego 12 miles", I will probably note the tall buildings on the horizon and conclude that the arrangement makes sense.

[TheStranger]

to me, knowing the distance to the downtown is universally more useful.  if I see a sign saying "San Diego City Limits" and - just past it - one that says "San Diego 12 miles", I will probably note the tall buildings on the horizon and conclude that the arrangement makes sense.

IMO, it would make much more sense to sign that as "Downtown San Diego - 12 miles", in the context that there are other in-town destinations within the city limits that out-of-town travelers are looking for that are not in the downtown area (i.e. Sea World, Jack Murphy (ahem, Qualcomm) Stadium). 


I can see where simply measuring for the "city" limits is problematic there - San Ysidro and La Jolla are both part of the city, yet are so far from the core that to simply measure up to that would be confusing.  For places like San Francisco, this would never be a problem...for an area like Sacramento, it depends on what direction one drives in.

[triplemultiplex]

When approaching Milwaukee from most directions, distance to Milwaukee is usually to the Marquette Interchange; so downtown.  And I believe this is standard practice across the state to use either a central point in a community or a major junction in the case of a large city.
In most cases I would expect the distances to city center.
Now it might make sense to use corporate limits in places where the city has been landlocked by suburbs and the distance will not change as a city sprawls out.

In the case of traveling on an interstate or similar facility, there's an assumption that the distance given to the next small community will be the distance to the exit one would take to go into the actual town.  (Unless said community is a significant distance off the highway.)

[huskeroadgeek]

For most large cities you also go through some suburbs before you reach the main city. That makes the actual city limit even less important. A traveler feels they are in the city before they are actually within the city limits of the city. A person traveling across Illinois on I-80 feels like they've gone through Chicago, even though they never entered the city itself. And for a city like Chicago where you go through a number of suburbs before you reach the city itself no matter which direction you are coming from, measuring the distance to the city limits really makes no sense.
I agree that as a traveler gets closer to or within the main city, it makes sense to make it clear that the distance given to the city is for downtown to distinguish between it and other destinations within the city. But from a longer distance, the downtown area is a good neutral point to measure distance to.

[roadfro]

From what I understand, Nevada mileage signs use the distance to the main post office of a city. An exception occurs with Las Vegas, which uses the Spaghetti Bowl (I-15/I-515/US 93/US 95) interchange as the measurement point.

The advantage of using a central point such as this is that it keeps mileages consistent. In places where there's still room to expand, measuring distance between city limit lines becomes inconsistent. Las Vegas has been constantly annexing land on it's northern and western boundaries over the last two decades...that would have meant the distance between Las Vegas and Beatty (and other points north on US 95) would've shortened by about 3-5 miles over the last 20 years even though there's been no alignment changes over that period.

[Chris]

I remember driving in Germany, and while I was driving through the outer neighborhoods within the city limits of Berlin, I saw signage that indicated "Berlin 30 km". I always found that was pretty weird. The Dutch cities aren't big enough to notice this, as distance signs within city limits pointing to the center are rare, but Germany has some pretty big cities, area-wise. The population density of Berlin is approximately 9,900 people per square mile, which is comparable to the denser suburbs of Los Angeles.

[J N Winkler]

One way around this problem, which is common in Europe but is ignored in the US in favor of the clumsy alternatives "Downtown," "City Center," "Civic Center" etc., is to use a city-center symbol (square with center dot surrounded by multiple concentric circles) next to the city name and distances that refer specifically to the city center.  (To be fair, though, this is not universal even in Europe:  "Zentrum," "Sehir Merkezi" etc.)

[bugo]

In Arkansas, Missouri, and Oklahoma at least the signs measure the distance to a point near the center of the city. 

[Revive 755]

In Arkansas, Missouri, and Oklahoma at least the signs measure the distance to a point near the center of the city. 

Not always for Missouri; there is one sign for EB US 40 on SB Ballas Road that gives the distance to about the St. Louis city limit instead of downtown.  There used to be at least one more on another interstate exit that also gave the distance to the St. Louis city limit, but I think it has been replaced.

[bugo]

In Arkansas, Missouri, and Oklahoma at least the signs measure the distance to a point near the center of the city. 

Not always for Missouri; there is one sign for EB US 40 on SB Ballas Road that gives the distance to about the St. Louis city limit instead of downtown.  There used to be at least one more on another interstate exit that also gave the distance to the St. Louis city limit, but I think it has been replaced.

The signs on northbound US 71 show the distance to the center of Kansas City.  When I lived there, I lived about 10 miles south of downtown, so I would subtract 10 miles from the distance to get the distance to my house.

[thenetwork]

ODOT has no uniform definition of measuring distances -- especially in the Cleveland area:

I-71 and I-90 west of downtown define "Cleveland" on the BGSs as the intersection of the two interstates @ I-490. I-90 from the east, IIRC, defines "Cleveland" as the I-90/SR-2 Dead Mans Curve split -- 4 miles from the I-490/I-71 interchange.


Meanwhile, I-480 in the Twinsburg area (Near SRs 82 & 91, east of Cleveland), have/had some BGSs define "Cleveland" as only 17 miles away.  17 miles only gets you to somewhere near the I-77/I-480 "Cloverleaf" interchange -- at least 6 miles away from either I-490/I-71/I-90 or the I-77 northern terminus at I-90 which would be the most logical route to Downtown Cleveland from the east via I-480. 

The only possible way that the 17 miles might be accurate is if you follow SR-14 exclusively from the I-480/SR-14 multiplex down Broadway Avenue into downtown.  Shortest route to downtown Cleveland mileage-wise?  Absolutely!  Quickest or most logical route to downtown Cleveland?  No freakin' way, unless you timewarp back to the early 60's!!!

[golden eagle]

I think measuring distance to the center of the city makes the most sense, because it's a consistent point that can be agreed upon that has significance as a destination. The outer city limit of a city many times is nothing more than an imaginary line that has no significance as an actual destination to measure to.

I'll agree with you. City limits can and will change. At least an intersection or a center point won't. Case in point: A mileage sign on U.S. 49 on the south side of Hattiesburg lists Gulfport as being 61 miles away. Years before, it used to be 69. Gulfport had annexed a section of Harrison County north of the city known as Orange Grove, which would explain the "shorter" distance from Hattiesburg to Gulfport (and almost doubling the population). If I weren't the geography geek that I am, I would think that I wouldn't reach Gulfport until I got to I-10 or just a wee bit northward.

Here's something to chew on: when driving towards Tuscaloosa from Birmingham on I-20/59, the Tuscaloosa city limits begin around the Mercedes plant, but just a little bit down the road, you'll see a mileage sign that lists Tuscaloosa as being another 18 miles! Again, if I were an average traveler, I'd guessed that I wasn't in Tuscaloosa until I got to McFarland Blvd. This Wikipedia map of the Tuscaloosa city limits seem to show that the area I'm speaking of is only along the interstate (which could be indicated by the slither of land stretching out eastward from the main part of the city). I'm guessing that's for police purposes (read: to catch speeders for city revenue).

[agentsteel53]

the area I'm speaking of is only along the interstate (which could be indicated by the slither of land stretching out eastward from the main part of the city). I'm guessing that's for police purposes (read: to catch speeders for city revenue).

Gerrymandering for fun and profit! 

[golden eagle]

Hattiesburg's city limits does the same thing along U.S. 49, except it doesn't stretch as far as Tuscaloosa does on 20/59.

[Greybear]

To quote the official Arkansas state map, published annually by the AHTD:

"Mileages to Little Rock are calculated to Junction I-30 and S.H. 10 (Clinton Avenue Interchange). Mileages shown to not represent the shortest route."