As mayor, Tanzler initiated a number of projects to revitalize Jacksonville's downtown with new revenues brought in by consolidation. Among the projects were the creation of what is now the Downtown Campus of Florida State College at Jacksonville, the construction of a large-scale public health facility, and the completion of major commercial construction projects including the skyscraper now known as the Wells Fargo Center. His most lauded contribution was his effort to clean up the St. Johns River, toward which he implemented sewage treatment and other environmental regulations. Tanzler was reelected in 1971, after defeating former Jacksonville mayor and Florida governor W. Haydon Burns, a "black hat" anti-consolidation activist, in the Democratic primary, and then easily winning the general election.