Map Zipcode Error Discovered

[+fly46]

I was looking for nearby benchmarks and clicked on the map to see how far my cache was from it. When I found my cache on the map, the map showed my cache to be in the 44068 zip code. The zip code that is shown starts a minimum of 1/2 a mile away from my cache. This erronius zip code - as well as another neighboring zip code - 44005 - are post office specific zip codes as well. (They're both only used for people with post office boxes.)

 

While this problem might not be a problem for me, I'm sure that people not familliar with the areas in question might be confused when trying to hunt. Also, woldn't this problem effect the caches when you do a zip code search?

 

The page to one map in question Slightly off the page view of this cache (north one click), is GCJ46G. The zip code shown doesn't start until the other side of the rail road tracks visible in that frame. The zip code for my cache should be 44048.

[+pdxmarathonman]

people not familliar with the areas in question might be confused

Once they start searching based on the coords I doubt the confusion will last.

[+fly46]

people not familliar with the areas in question might be confused

Once they start searching based on the coords I doubt the confusion will last.

You've never checked the cache maps before you headed out if you were going somewhere you wern't familliar with? I'm quite sure I'm not the only cacher that will sit there and be like "I'm going to town ABC wonder what is there" and then if I saw that what I was looking at was miles from where I was going and apparently in another zip code, I'd think twice before I went.

 

Or how about the people that can't use their GPS in the car to get to the general location of a cache. Because zip code confusion on the map wouldn't put them a few miles off if they were familliar with, say, the general area of the town, but not with the particular street that the cache was on and went to a parking lot in town and discovered that they had to walk 4 miles down a sidewalk to a cache that should be a park and grab?

[+Mopar]

A quick use of the search feature turns up what appears to be your answer:

 

Perhaps you can inquire at the Census department? The data originates from them.

 

Jeremy Irish

Groundspeak - The Language of Location 

 

From the Census Bureau's TIGER FAQ:

 

We have produced, as a by product of other work, a point file containing a calculated internal point. This point was calculated in the computer from the locations of addresses with a specific ZIP Code and not out in the field using the Global Positioning System. Note, since ZIP codes are not specifically designed to be polygons (they are linear postal delivery routes) a given calculated internal point could be well away from the addresses it represents such as addresses clustered along an arc. An example would be addresses along a long arc-shaped street. Also, the file doesn't have ZIP Codes for completely commercial areas or for places with non-city-style addresses (most of the rural areas).

 

The Census Bureau's FAQ has been updated since that post. The latest version may be clearer:

There are a variety of reasons why you're having this problem. First, we

don't have complete ZIP Code coverage in TIGER because we don't have complete

address coverage for the entire country. We only have city-style addresses in

our data base. P.O. boxes and rural route addresses aren't particularly

useful to us for taking the census. We have to use the more traditional

"knocking on the door" approach to insure that we have complete coverage.

This means our address, and therefore ZIP Code, coverage is not good in the

rural areas.

 

A more basic problem is that ZIP Codes were not developed as polygons by the

Postal Service, but as a way to manage mail carrier routes. This means that

they are really a collection of linear features (carrier routes) at best.

Many, particularly in urban areas, can be encompassed neatly by an imaginary

polygon. That can't be done easily (or at least accurately) in many other

areas, particularly rural. In rural areas there is not necessarily a complete

assignment of all land area to one or another post office. By that I mean, a

ZIP Code is really a point feature (assigned to a post office, really a

building). It may provide some, or no, house delivery service. People can

more or less go the one that is closest or most convenient for other reasons

to get their mail.

 

The ZIP Code maps produced by mapping companies aren't being made using an

authoritative cartographic boundary file coming from the USPS (in our dealings

with them we haven't found one). They are the result of these companies

making their own judgments and using a variety of sources to come up with an

unofficial map.

Edited August 6, 2004 by Mopar

[Jeremy]

Please send approximately $30k to our PayPal account (paypal@Groundspeak.com) and we will purchase better maps to fix this zipcode problem.

[+bitbrain]

Please send approximately $30k to our PayPal account (paypal@Groundspeak.com) and we will purchase better maps to fix this zipcode problem.

PayPal says I have to verify my account before I can send that much. What's up with that?

[Charles Iverson]

yeah same here whats the deal with that