I will present an analysis of Galactic halo structure and substructure traced by~500 RR Lyrae stars in the SDSS stripe 82 region. The main result of this study is a 2D map of the Galactic halo that reaches distances of 100 kpc and traces new and previously known halo substructures, such as the Pisces and Sagittarius tidal streams. I will also present strong direct evidence, based on both RR Lyrae and main sequence stars, that the halo stellar number density profile significantly steepens beyond 30 kpc from the Galactic center. Using a novel photometric metallicity method that simultaneously combines data for RR Lyrae and main sequence stars, I will show that the median metallicity of the Sagittarius trailing stream in the SDSS stripe 82 region is [Fe/H]=-1.2 +- 0.1 dex. In addition to these results, I will also present my ongoing work on a 3D map of the Galactic halo constructed using a sample of 4000 RR Lyrae stars that cover 8500 deg^2 of northern sky and probe up to 30 kpc from the Sun.