Northern red oak (Quercus rubra L.) is one of the most economically and ecologically significant trees in contemporary forests of Eastern North America. Despite the importance of this species, little is known about its genetic diversity and population dynamics. In the following set of studies, I investigate the neutral and adaptive genetic variation in Q. rubra and present a sequence of the LSC region of its chloroplast. I first investigated genetic diversity and differentiation of 6 populations in the UP (the Upper Peninsula, Michigan) and Isle Royale National Park. I found that one of the populations showed low diversity and high differentiation in comparison to the other 6 UP sites. I then observed the rangewide genetic diversity and differentiation of Q. rubra. I found that the UP populations were highly differentiated from the rest of the range and that populations in Vermont show high genetic structuring. I used a subset of the populations from the rangewide study to detect evidence of adaptation in cold tolerance genes in Q. rubra. I found that ICE1 and HOS1 showed evidence of past selective sweeps. This is the first study to investigate the population genetics and genomics of Q. rubra on a rangewide scale.