Media guides in general date back to the 1920s, [and the earliest World Series media guide at the National Baseball Hall of Fame is 1966.] The 4″ x 8.5” format was standard for many years, even after the guides went from three staples down the middle to a glued spine as they expanded so the guide could easily fit in a man’s jacket or pants pocket, or in a standard #10 envelope. [They changed to a spiral spine in 1996. From 1966 to 1973, each league put out separate guides for the World Series.] For years media guides did not include any price on the cover, as they were intended to be given by the team to sportswriters (“media”). Hence the name. But their popularity grew and starting in the 1970s teams realized that the public had an insatiable thirst for information—historical, statistical, and personal—about ballplayers. Most teams also include photographs and brief biographies, and “behind the scenes” staff, such as team physicians and the non-uniformed staff (ticket manager, stadium manager, organist, public address announcer, etc.). There is also usually a section on former team members in the National Baseball Hall of Fame and on those enshrined in the team’s own hall of fame. With the advent of the World Wide Web, much of the information contained in printed media guides can now be obtained instantly online from official team websites.-- https://sabr.org/journal/article/media-guides/