You can drive all around the Treasure Valley looking for the most rare Pokemon or you can drive around and open an app that tells you where each one is. I just tried it and the app works. 

Pokemon Go is about teamwork. If you see a rare Pokemon, report it and their location. Other people are doing the same.

Download Poke Radar and allow it to access your location.

 

Once you are located...

 

 

Closest to me is...