Can I make a DISCOUNT CODE only active in USA

My store will be shipping large items. I want to use free shipping discount codes but only within the US. Free shipping around the world be a disaster. 

Alternatively I might be able to work around this if I can make free shipping codes NOT COMBINE with any other discounts. 

Is there a way I can do either of these? Thanks!

if you set up shipping options, you'll be able to create free shipping codes just for specific shipping options, i.e., shipping codes for US, Canada, international, etc. when you create a free shipping code, you'll be able to choose which option you want the code to apply to. unfortunately, there is no way to make free shipping codes not combine with other discounts. you can set your free shipping code to apply to orders over a certain amount -- i.e., free shipping on any order over $100.