Create search URL with search-term in it

Hello all,

here is a problem I would like to know the solution to. Certain search boxes, upon entering a search term and hitting enter, they do return the results of the search but the URL of the results page does not contain the search term used in it. Which, for example, in practice one cannot bookmark this particular search page.

Example:

Mobile tracking for USPS. Go to:
http://m.usps.com/MobileTrackPackage.aspx

You see the search box and you enter a tracking number, say LJ631039586US, then the URL it takes you to does not have the trackign number in it.

Any ideas/suggestions?

Thank you