Populate dropdown with records from a related module

I have a module called "States" which contains 51 records of data for the US states. I now need to have data for ZIP codes, which I'm thinking of storing in a module called "ZIP codes" with a One (state) to Many (zip codes) relationship. Is it possible to create a dropdown field populated with the States records and a second dropdown populated to the related ZIP code records, based on the State selected.

The data in the selected ZIP code record will then be used in a mathematical calculation.

We have SugarCRM Professional on demand