Chocolate residues left on ancient jars mark cacao's earliest known presence north of what is now the U.S.-Mexico border.

The residues, found on pottery shards excavated from a large pueblo (called Pueblo Bonito) in Chaco Canyon in northwestern New Mexico, suggest the practice of drinking chocolate had traveled from what is now Mexico to the American Southwest by about 1,000 years ago.

Scientists have known about the early uses of chocolate in Mesoamerica, with evidence for rituals involving liquid drinks made from cacao beans dating back more than 1,000 years. (Mesoamerica extends from central Mexico to Honduras and Nicaragua.)

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