Instructions
Launch "SimCity 4."
Click the "Region View Options" icon at the top left corner of the screen. This icon is a picture of a grid and displays "Region View Options" when the mouse cursor is placed on it.
Click the "Create New Region" icon. This icon is of two squares on top of one another that displays "Create New Region" when the mouse cursor is placed on it.
Type a name for your region in the blank "Region Name" field.
Select either "Plains" or "Water." Whichever option is selected designates the majority of the terrain in the region.
Click "Create Region." Your new region is created and you can begin building cities on it immediately.