Mapping the Universe with 4m Telescopes

The availability of wide-field telescopes equipped with CCD imaging cameras and, more recently, very wide field spectroscopic capabilities, is revolutionizing discovery in astronomy. I will describe the Legacy Surveys project which has created one of the largest, public, deep optical catalogs of the sky. The Legacy Surveys is being used for selecting targets for a cosmology survey with the Dark Energy Spectrospic Instrument (DESI). I will present an overview of the goals, construction, and current status of the DESI project, which aims to create the largest cosmographic map of the universe and investigate its expansion history with unprecedented precision, as well as map the kinematics of many millions of stars in our Galaxy.