Adding City field to an existing spreadsheet

I have a spreadsheet of over 8000 addresses. I have the street, state and zip but not the cities.

Is there a way I can do a search and mass import of cities from a website, like USPS? I'd like to know if there is something I can do quickly rather than manually look each zip code up and enter it in one by one.

Thanks,

Look here:

http://www.unitedstateszipcodes.org/zip-code-database/

Has both an Excel file and a CSV type file.

With the Excel you only need do a VLookup and match the Zip Codes and pull out the city.

You will probably still have to make some manual adjustments, but it should be minimal.