Oaks are principally temperate zone trees or shrubs, estimating about 600 species globally. Oaks have remained on the non-glaciated territories of North America following the Cretaceous Period. According to the U.S. Forest Service , 50 oak species are represented in 2/3 of the eastern North American wood cover types and dominate 68% of hardwood forests (77 million hectares or 191 million acres). Reddit user: BRENNEJM. Data: http://github.com/wpetry/USTreeAtlas Oaks of the United States Quercus alba Quercus arizonica Quercus arkansana Quercus bicolor Quercus chapmanii Quercus chrysolepis Quercus coccinea Quercus douglasii Quercus dunnii Quercus durandii Quercus ellipsoidalis Quercus emoryi Quercus engelmannii Quercus falcata Quercus gambelii Quercus garryana Quercus georgiana Quercus glaucoides Quercus graciliformis Quercus gravesii Quercus grisea Quercus havardii Quercus hypoleucoides Quercus ilicifolia Quercus imbricaria Quercus incana Quercus kelloggi