say the distance to the city limit or the city center?
The standard calls for listing the distance to the city hall. Likewise, elevations for cities shown on road signs are at the city hall.
I contend that the distances are only rough estimates to some reasonably close portion of the city or town.
On the interstate that runs through my community, there are two signs for distance to my town. The first says “Swansea 12.” Drive four miles down the road, and the next one says “Swansea 10.” Neither of them are correct.
I also noticed on I95 through Connecticut: “New Haven 55.” Drive 8 miles: “New Haven 50” Those signs were close (about 52 and 44 miles), given the distance from the Elm City.
Maybe out west they’re more accurate.
I don’t know about mileage signs on highways and interstates, but I believe that cartographers use post office to post office to calculate distances between cities. That would of course the main post office in within the city limits.
From my surveying days I know that in Australia they were measures to the central Post Office.
Supposedly, the mileage signs leading to New York City give the distance to Columbus Circle (59th Street & Eighth Avenue, Manhattan).
I know in Lexington, Kentucky there is (or was several years ago anyway) a Zero Mile Marker in front of city hall with a sign that said something like “Distances to Lexington to be measured from this point in all directions”.
I had always heard the measurements were supposed to be to city hall.
City hall.
One explanation for the discrepancy in freeway signs, is when you’re closer to the destination, the mileage given is to the city center exit, not the actual city. If that makes sense.
So, it might be 16 miles to CITY, but the exit one would take to actually get there is 13 miles away - say the sign you see is at exit #100, and the exit you’d take to city center is # 113. Freeway mileage signs generally indicate the number of miles to the freeway exit rather than the destination itself.
I was told at one time that this was true in the US, also. I’ve actually tried it and it seemed to work (that if i drove to the main PO, the mileage would be, at least, very close).
But, we don’t even have a main PO anymore (at least downtown in Denver) so I haven’t any idea where they measure distance to anymore.
Bob
I’ve always heard “post office” or “city hall” and so on – but who goes to those places? I mean the great majority of people that have an interest in getting Detroit (for example) don’t give a darn about post offices or city halls; they just want to know where the city limit is, right?
Wouldn’t that be equally useless, if not more? If they don’t know where the city limit actually is, they don’t know where their destination is relative to it.
Well, if you know you’re going to “Utica” then knowing where the city limit is will certainly help you when it comes time to start looking for your destination. “Is M59 right at the border? Is it at the far side of town? Roughly in the middle. Oh, look, Utica’s still eight miles away; I don’t have to worry about it yet. Oh, crap, ‘Welcome to Utica.’ I better start looking for M59.” Granted that doesn’t apply to freeways, where it’s just easier to look for mileage markers. In that respect, though, my non-GQ subjective preference is the city limit, because then I can say, “Wow! I’m in Denver! I’ve never been here before.” And then I can get excited and say, “Wow! Cheyenne’s only 180 miles away, and I’ve never been there, either!” 
The obvious point that should be used is the geographic center of the city.
…which can change as the city grows, right?
Both Paris and Madrid have a kilometre zero marker in the side walk. This where all distances are measured from, for the whole country. The one in Paris is just outside Notre Dame cathedral, the one in Madrid is in the Puerto del Sol. This is the London marker.
The location of City Hall can change, also. Here in Seattle we’ve been arguing for several years about how much of a particular downtown skyscraper city government should occupy and whether or not “city hall” should be so designated.
WA Speculation time: I’m guessing that these conventions arose in the 19th century, and that for most American towns it made little or no difference whether measurements were made to City Hall, the railway station, the Post Office or to the main street (or Main Street).
I always understood it to be the City Hall, for the reason demonstrated by the following anecdote:
There used to be (don’t know if they’re still there) two signs posted just as you entered Metro Toronto’s city limits southbound on highway 404. The first said:
Welcome to Metropolitan Toronto. Population [whatever].
The second sign was a distance sign, and it said:
Toronto (City Hall) 27 km.
Now, the “city hall” rule might not hold elsewhere, but certainly in Toronto’s case, distances seem to be measured from City Hall.
How do I find out what route is the mileage is based on? I’ve always been curious about this.
For instance, if I’m going into NYC, and I’m on route 17 (or any other road for that matter) and see a sign that says “New York City…98”, at that point there are a half dozen different ways I could go into the city. Does the 98 miles represent the shortest possible way?
As a child I was always told that road distances were measured from the obelisk in Macquarie Place. Presumably that was only a colonial practice.