Noycwild
You really need to rethink your database design. Having a table for each State is definetly not the way to go.
A much better structure would be to have the following structure
1/ a STATE table that contains a record for each state.
2/ a TOWN table that contains a record for every town and includes a FK relationship to the PK of the STATE table
3/ a STREET table that contains a record for every street and includes a FK relationship to the PK of the TOWN table.

With this structure you can populate your State combo from the STATE table. When the user selects a State, you can pass the value of that combobox to a SQL statement that poplates the Town combo. Repeat this process to populate the Street combo based on the value selected in the Town combo.