Zend certified PHP/Magento developer

Store code being automatically added

A store is setup with multiple websites, with a single store and store view within each website.

magento-vars.php was updated with MAGE_RUN_CODE matching the store code. Base URLs are set.

Correct store loads for each configuration.

Problem: even though base URL for each store ends in .com/, a redirect is occurring from .com/ to .com/store_code_here. How can I prevent it from doing this redirect, and to avoid the store code being part of the URL?