I added a new region line to my .info file under /sites/all/themes/[theme] directory. However when I look at the Blocks page, the region is not visible, nor is it a selectable item from the dropdown menus. I've cleared the cache as well. What am I missing?
If you have multiple themes enabled, make sure you are looking at the correct theme on the block configuration page.
For example, if you have custom_theme and garland enabled, there is a block configuration page for each.
Go to http://www.example.com/admin/build/block/list/custom_theme to see blocks for your custom_theme
Go to http://www.example.com/admin/build/block/list/garland to see blocks for the garland theme
etc... for all enabled themes