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.

https://twitter.com/Peets_Tweets/status/648883346936696832

https://twitter.com/WholeFoods/status/648089720292024320?

https://twitter.com/DunkinDonuts/status/648859781504086016?

https://twitter.com/krispykreme/status/648838316679294976

https://twitter.com/Starbucks/status/648837161035284481
 

https://twitter.com/McCafe/status/648844307772907520