(San Francisco) San Francisco. June 20 (Cal.). Perfectly struck straight line with manuscript magenta date & matching "80" double rate on immaculate 1849 cover to New York, manuscript endorsement "Per Steamer Panama", Extremely Fine and choice, possibly the finest known example of this first day of usage of the San Francisco straight line, ex-Knapp, Nathan. Estimate  $1,000 - 1,500. $0 (Image)