Sometime we need to have dropdown for states related to countries just as we have for United States by default, for that we need to add states of particular country. To add custom states we need to modify the tables of magento. There are two tables involved in the addition of states -

1) directory_country_region
2) directory_country_region_name

To add states we have to run this query -

e.g. To add India states in database -

INSERT INTO directory_country_region (region_id, country_id, code, default_name) VALUES
    (NULL, 'IN', 'DEL', 'NEW DELHI');

INSERT INTO directory_country_region_name( locale, region_id, name ) 
SELECT 'en_US' AS "language", region_id, default_name
FROM directory_country_region
WHERE country_id = 'IN';

Where directory_country_region is used to show states for a specified country_id in the State/Province drop box on the address forms.

We need to add corresponding record to directory_country_region_name , in which we enter the region_id generated by inserting record in directory_country_region , this entry create new region shown in email or order summary.