Chocolate had been popular in Mesoamerica before the arrival of Europeans. However, the methods in which this was consumed were very different from the way chocolate was consumed in Europe after the conquest of the New World, or from the way we consume it nowadays.
After 1876 in particular, the consumption of chocolate rose for two main factors. First, the invention of "Dutch cocoa" allowed chocolate to be solid. Before this, chocolate had only been consumed as a drink, but this allowed people to enjoy it in bars. The second factor was the addition of powdered milk by Daniel Peter and Henri Nestle, creating milk chocolate.