>Calculating the exact distance for every possible 'destination' seems like overkill?
>If this is for the U.S. and only targets within a certain radius are required you could get a rough selection based simply on latitude and longitude.
>There's pretty much a direct correlation for latitude (110 miles per degree) and given that the the U.S only extends from about 45-25 degrees it will always be between say 80-100 miles per degree of longitude. So grab the max by allowing an extra 20% on longitude then do the exact calculation on that result set? Not having the meridian pass through the country makes it easier as well.....

So basically, we could simply rely on the Latitude and Longitude fields to apply our queries on. Is that correct? So, for example, if I want a radius of 20 km, what kind of +- formula should I calculate to allow + or - radius on the Latitude and Longitude?