A two-color study of the galaxies detected on POSS-I in a 289deg^2^ region centered on the North Galactic Pole is presented. We use a variety of mapping techniques to characterize the large-scale spatial distribution of galaxies. The depth and sample size of this new survey allows, for the first time, the isolation of large photometric subsamples of galaxies in high- and low-density environments on the scale of superclusters. Our principal finding is a statistically significant difference between the mean photometric properties of these subsamples in the sense that galaxies in the high-density Coma and filament environments have redded colors and larger concentration indices than galaxies drawn from low-density interfilament regions. These results are in agreement with the known morphology-density relation.