From: Daevid Vincent
Date: April 25 2006 7:43am
Subject: RE: Calculate LONG/LAT from ZIP+4 (positve vs. negative longitude)
List-Archive: http://lists.mysql.com/mysql/197296
MIME-Version: 1.0
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: 7bit

I'm so confused. I'm finally getting around to needing to do a 'store
locator' thing.

I procured myself some zip/lat/long databases from various places. Then I
noticed that for the same zip code, I got different values in different
databases??!!!

So for a sanity check, I decided to look "online" and punch in some to see
what the "real" lat/long should be. Well, different sites give different
values, and not only are they "slightly" off, but sometimes they're
_positive_ or _negative_!? UGH!

http://www.zipinfo.com/cgi-local/zipsrch.exe?ll=ll&zip=98119&Go=Go
Seattle WA 98119 47.6388 122.3700 
http://www.census.gov/cgi-bin/gazetteer?city=&state=&zip=98119
Location: 47.637917 N, 122.364272 W

http://www.csgnetwork.com/cgi-bin/zipcodes.cgi?Zipcode=98119
http://www.myzipdb.com/mzdb_demo.php
http://www.nearby.org.uk/coord.cgi?p=98119
City Seattle 
State Abbreviation WA 
State Washington 
Latitude 47.638770 
Longitude -122.366941 

So I try the east coast: 

http://www.zipinfo.com/cgi-local/zipsrch.exe?ll=ll&zip=14526&Go=Go
Penfield NY 14526 43.1532 77.4485 
http://www.census.gov/cgi-bin/gazetteer?city=&state=&zip=14526
Location: 43.139638 N, 77.456043 W

http://www.csgnetwork.com/cgi-bin/zipcodes.cgi?Zipcode=14526
http://www.nearby.org.uk/coord.cgi?p=14526&f=full
City Penfield 
State Abbreviation NY 
State New York 
Latitude 43.145342 
Longitude -77.458499 

Please help me to understand WTF is going on? 
Which lat/long do I need? 
How does the negatives effect the magic formulas to calculate distances? 
(I'm no trig wiz). 

I assume that the more precise the numbers, the better the results will be. 
To what decimal point should I be concerned with?