Magento: Get State Code, ID, Name from Region ID

Get state code from state id

$region = Mage::getModel('directory/region')->load(12);

$state_code = $region->getCode(); //CA

Get state name from state id

$region = Mage::getModel('directory/region')->load(12);

$state_name = $region->getName(); //California

Get state id from state code

$region = Mage::getModel('directory/region')->loadByCode('CA', 'US');

$state_id = $region->getId(); //12