Denver-based Chipotle Mexican Grill, with 500 restaurants nation-wide, is the largest restaurant seller of naturally raised meats in the USA. The restaurant is increasing the use of organic black and pinto beans, and the company plans to add more organic beans as supply allows. In June 2006, Chipotle placed ads on the side of Denver buses combining humor with their commitment to serve natural meats. Chipotle announced it would donate up to $50,000 from their guacamole sales to The Land Institute, an organization that researches environment-friendly farming techniques.