How can I add in new Locales to the locale list? I have a site that has a few different countries that speak the same language but want to have them as different Locales. 


Mexico (english)
Mexico (spanish)
USA (english)
USA (spanish)
Peru (english)
Peru (spanish)


These might all share some content but the manager of each region might want to change the content for their own region.

How can I add in new Locales in the locale list in Craft?
There are several locales that Yii comes with but Craft doesn't, simply to keep Craft's filesize down a bit (they add a lot of weight). You can see the master list of Yii locales here: https://github.com/yiisoft/yii/tree/master/framework/i18n/data   - If you see a locale in there you want that Craft doesn't come with, just view the raw version of the file on GitHub and then save it to your craft/app/framework/i18n/data/ folder. Then Craft will start supporting it.

If you need a locale that Yii doesn’t offer, find the closest locale Yii/Craft does come with, and copy it with a new name (e.g. en_us.php => en_mx.php).