On the US Postal Service site, you can lookup a city based on a zip code passed from the page. You can also lookup a zip code based on a city. What I am trying to guess here is the exact URL to pass (in VFP) including a Zip Code parameter without going to the site itself. I am trying to deduce guesses by looking at the source of the page itself. For example, with Web Connect, I put the name of the function to call, then the parameter(s) separated by tildes [i.e., ~]. If anyone can tell me if this is possible, has anyone done this, what some good guesses would be, I would be most appreciative.

For a start, see:

USPS

then view the frame source.

Many TIA!