Native resolution: (16) .. left hand menu, there's a dropdown called " Display" Open that up and find "Manage Custom Resolutions ".
I can only select three resolutions. (too sma. BTW, In need you can creat custom resolutions too, keeping the aspect ratio intact.
and To set a custom resolution in SimCity 4, you need to change the target of your SimCity 4 shortcut. To do this, right click. EA Cricket 2007 Custom Resolution/Change Resolution