SAN DIEGO (CBS 8) - Millions of Americans will be on an extra caffeine high Tuesday in celebration of National Coffee Day.

A number of coffee, restaurant, and grocery chains are offering free or discounted coffee for the day. They include, Dunkin' Donuts, Krispy Kreme, McDonald'sWhole Foods and Peet's Coffee & Tea.

On the environmental front, Starbucks is launching a tree-planting initiative.