In the 1.30.7 theme version we have added a new connection between City and State/County taxonomies.

Step 1 Edit City

Step 2 Choose a State/County from the dropdown

On new city creation, if a State/County is not assigned, the first one from the list will be automatically assigned.

After the connection is done, in filter area in Properties List pages (Properties List standard, Properties List Half map, Properties List Directory ) and in advanced search fields, for City field will be shown only the ones assigned to the selected State/County

How to attach City to State, and Area / Neighborhood to City