AbstractThe morphological and chemical structure of the Milky Way today is an important constraint on models of the formation and evolution of the Galaxy. We use H ii regions, the sites of recent massive star formation, to probe both the Galactic spiral structure and the Galactic metallicity structure. H ii regions are the brightest objects in the Galaxy at radio wavelengths and are detected across the entire Galactic disk. We derive the distances to H ii regions using parallax measurements or by deriving kinematic distances. Here we summarize ongoing work to assess the accuracy of kinematic distances and to complete the census of Galactic H ii regions in the Southern sky.