 Denver gained back the population it had lost during the depression, mainly through the annexation of neighboring towns, and ended the century with a population of more than 133,000.The Progressive Era brought an Efficiency Movement typified in 1902 when the city and Denver County were made coextensive.In 1904 Robert W. Speer was elected mayor and initiated several projects that added new landmarks, updated existing facilities, or improved the city's landscape including the City Auditorium, the Civic Center and the Denver Museum of Nature and Science.