I was very worried about finding food on our recent vacation in Bolivia, Peru, and Ecuador. Happycow was a lifesaver! In LaPaz Bolivia, we found the best restaurant anywhere through happycow - Ali Pacha!
I have used this app successfully while traveling in Colorado and Arizona. Listings along with the restaurant ratings and reviews on this site have made traveling as a vegan much easier.
My only complaint is that a business must have more than one vegan option to be listed on the site. That means tha, in sparsely populated areas, nothing is listed even though there may be one restaurant with a vegan option.
Hiking Sandra about HappyCow - Vegan Food Near You, v3.4