The production code listed for The X-Files pilot episode is 1X79.
“Pilot” is the first episode of season 1, but its production code is not 1X01. The code 1X79 is the identifier shown in the episode’s production information and is used in series documentation alongside details such as Chris Carter’s writing credit, Robert Mandel’s direction, and the September 10, 1993 air date.
Production codes can be confusing because they do not always match a show’s broadcast numbering. In this case, 1X79 belongs to the pilot’s internal production history, while “Pilot” is conventionally described as season 1, episode 1. The code therefore should not be confused with a later season code such as 2X79 or with a generic series label such as TXF01.
The pilot was produced on a budget of about US$2 million, with principal photography lasting fourteen days in March 1993. Although the story is set in Oregon and Washington, D.C., filming took place in and around Vancouver, British Columbia. The series continued producing in the Vancouver area for its first five years.