When the Air Mail Act of 1925 was passed, the City and County of San Francisco recognized the economic importance of establishing a municipal airport as the western terminus of a transcontinental airmail route. No less than nine possible sites were identified in and around the city and as far south as Redwood City, but ultimately the terms presented by Ogden Mills for pasture land he owned next to San Francisco Bay, fourteen miles south of the city’s Civic Center, were the most economical. On March 15, 1927, a three-year lease between the Mills Estate and the City and County of San Francisco was signed for “an area of one hundred and fifty (150) acres, more or less, for the term of three (3) years at the annual rental of Fifteen Hundred and 00/100 Dollars ($1,500.00).” The property was officially designated "Mills Field Municipal Airport of San Francisco" by resolution on April 25, 1927. Because the airport was considered “experimental” and permanent plans were contingent on the results of meteorological studies, all the buildings constructed on the site were meant to be temporary. Image: Mills Field Municipal Airport of San Francisco, Administration Building, late 1920s. Gift of United Airlines Archives. 1999.047.227 This image was posted on May 03, 2017.