i just worked on this counties.
County codes are frequently used in delivery, invoice, and money transfer
addresses. The County form is used to create and view counties in the state
selected on the State form. Counties are unique to each state.
Use the following procedure to set up states:
1. In the Navigation Pane, click Basic, and then Setup > Addresses >
Country/region > States.
2. In the State form, press CTRL+N to add a new state (or click the
New icon on the toolbar).
3. The Country/region field is automatically filled with information
from the associated line in the Country/region form.
4. In the State field, type a unique identifier for the state.
5. In the Description field, type the official state name.
6. In the Intrastat code field, type the Intrastat reporting code. This is
only valid in Austria and Germany