When u add a .resx file to your application By default, a new folder that is named App_LocalResources is created. Additionally, a resource file that is named Default.aspx.resx is created.
This file contains information about each Controls . The values in the resource file match the values that you entered for each Controls in Design.
i know this is possible in MVC project u can try this use Resx Files Outside Of Special Resource Directories. and access it from there and If you add a resx file to any other folder in an MVC project or class library, the resx is automatically set to be embedded into the project’s output assembly
for more detail read this article
hope its clear