How to Build Targeted Traffic to More Then One Country at the Same Time!

How can I build and generate U.S. based organic traffic to a website and also to U.K. and Canada at the same time? Do I need to create and market a separate website for each country. i.e. U.S., Ca, U.K? or would i focus on just the U.S. then do PPC for the other countries instead?

Basically, i need to build as much organic (free) traffic as possible in the U.S., Canada and also U.K. locations at the same time.

Your helpful hints and tips, would be much appreciated!