When looking at the envelopes/addresses, the Zodiac Killer abbreviated the San Francisco portion of the San Francisco Chronicle and San Francisco Examiner into initials, when he mailed the July 31st 1969 Chronicle letter, July 31st 1969 Examiner letter, October 13th 1969 Paul Stine letter, November 8th 1969 Dripping Pen card, November 9th 1969 Bus Bomb letter, June 26th 1970 Button letter, July 24th 1970 Kathleen Johns letter, July 26th 1970 Little List letter, October 27th 1970 Halloween card (abbreviated twice) and April 24th 1978 "I Am Back With You" letter. The Zodiac Killer abbreviated to S.F. (using periods or full stops) on all the eleven occasions he adopted this format. From July 31st 1969 to April 24th 1978, only the Badlands communication failed to follow this pattern. When mailing the December 20th 1969 Melvin Belli letter and March 13th 1971 Los Angeles letters, he also used periods after abbreviating the addressee into initials. Even on the March 22nd 1971 Pines card, the Zodiac Killer pasted the initials S.F. using periods.
The Zodiac Killer used San Fran. or San Fran on the envelopes/addresses on eleven occasions between July 31st 1969 and January 29th 1974, but never once was this the last part of the address. The Badlands communication yet again broke with tradition, with the envelope ending San Fran.