Magento gives users the ability to restrict shipping to certain countries under specific shipping methods. However, the is no native functionality for restricting shipping to certain states within countries. Fortunately, there is a Magento Extension that can be configured to restrict shipping to certain states or provinces. This solution works for all shipping methods (UPS, USPS, FedEX, Flatrate, DHL, etc.).

Below we will provide instructions on how to install this extension and configure it to only allow shipping to the Lower 48 U.S. States.  There is also a video demonstration of the extension at the end of the post:

1. Install the Region Manager extension via Magento Connect.
2. Log into the Magento Admin panel and  go to  the newly installed Region Manager section:  System > Configuration > Sales > Region Management.
3. Click on Region Management and the configuration screen will be displayed.  Select New Region Configuration to add specific countries and set exclusions.
4. The Common Settings options can be used to pre-select certain settings / values for specific countries based on the site’s requirements, for example Lower 48 States excludes military locations, U.S. territories, Alaska, and Hawaii, while 50 States Only excludes military locations and US territories.
5. Once the options are configured as required, save the changes.  To restrict shipping to the lower 48 U.S. States, simply select that option under Common Settings.
6. Flush the Magento Cache:  System > Cache Management > Flush Magento Cache.
7. Test checkout to confirm that the extension is configured correct and excluded areas are not available.

The extension works by removing the excluded States or Regions  from all Store Views and Websites.  Excluded areas are not displayed as options for billing address, shipping address, estimate shipping, or customer registration.  For those who want flexibility to assign values to a specific store or area (i.e. allow customers to use Alaska as a billing address if they use an address in the lower 48 states for shipping) or have any other questions about installing and configuring this extension, please contact us.