I would use an Option Group and a command button.
The Option Group would have 3 buttons, one for each location and would
return 1,2, and 3 respectively.

The command button would open the form using the Where argument of the
OpenForm method to filter the form's records based on whatever field in the
form's recordsource that ldentifies the location.  For example purposes, I
will assume the field identifying the location is [Location] and that the
values for the locations are Denver, Chicago, and Dime Box (a small down in
SE Texas :)

The command click event would then be something like:

Dim strWhere As String

   strWhere = "[Location] = """

   Select Case Me.opgLocation
       Case 1
           strWhere = strWhere & "Denver"""
       Case 2
           strWhere = strWhere & "Chicago"""
       Case 3
           strWhere = strWhere & "Dime Box"""
   End Select

   Docmd.OpenForm "HelpDesk", , , strWhere