Autofill from a list

I have a call report summary that contains the city from which the call originated.  I need to be able to sort the data based upon the county from which it originated.  In a separate spreadsheet, I have a list of cities and their corresponding counties.  I need to be able to add a column to my call report summary and have that column populate with the names of the counties matching the corresponding cities.  I have attached a very simplistic version of my dilemma.  Any suggestions would be greatly appreciated.