What is the fictional date of the past events in "The City on the Edge of Forever"? That is not as easy to answer as one might think, because of the possibility that people in Edith Keeler's era might not use the same calendar era as most of us on this site use. Instead of counting the years from AD 1, the calendar era of the Anno Domini date system, they might count the years from some year that is before or after AD 1. After McCoy leaps through the Guardian of Forever: When Kirk and Spock arrive in the past: When McCoy wakes up in Edith Keeler's mission: This establishes that the present year in the calendar used by Edith Keeler is 1930.Since the Depression in the USA lasted from about 1929 to 1941, the year that Edith Keeler calls 1930 should be between about 1929 & 1941, and thus should have a calendar era between 1 BC and AD 11. Kirk and Spock discuss contrasting newspaper reports about Edith Keeler: Clearly Kirk and Spock are using the dates in the newspaper articles, which are not necessarily the dates used for this era in their own history books centuries later. And days later: So what is the evidence that the calendar used in this era might not count the years Anno Domini beginning with AD One, but count the years from a different calendar era? And: http://www.chakoteya.net/StarTrek/28.htm In the year 1930 in Edith Keeler's calendar, call it 1930 EK, Edith Keller assumes that people who know who Clark Gable is. https://memory-alpha.fandom.com/wiki/The_City_on_the_Edge_of_Forever_(episode) So when was Clark Gable actually a leading man in movies? The Internet Movie Database (IMDB) lists all of Clark Gable's movie roles. For North Star (1925) IMDB lists Clark Gable 6th in the cast. Second was Virginia Lee Corbin who turned 15 in 1925, and first was Strongheart the Dog. Yes, Clark Gable once played sixth fiddle to a dog! North Star (1925) was the second movie role that Clark gable was credited in, and the first where the character was important enough to be given a name. All his other early roles were as uncredited extras until 1931 when Gable was credited with 12 roles in various movies, billed between eighth in The Easiest Way and first in Sporting Blood. https://www.imdb.com/name/nm0000022/?ref_=tt_cl_t6 So as far as I can tell in our alternate universe people would have started talking about Clark Gable movies sometime in 1931. Therefore, it seems logical to suppose that either: 1) Star Trek is in an alternate universe where Clark Gable was already a movie star in AD 1930. or: 2) Star Trek is in an alternate universe where a different calendar era was used in 1930s USA, so that the EK (for Edith Keeler) year was 1930 when it was AD 1931, AD 1932, or later. Here is a link to an image of a scene from "City on the Edge of Forever" showing a calendar for a month. http://tos.trekcore.com/gallery/albums/1x28/cityontheedge_382.jpg In the lower left one can see a thin slice of a column with two parts of numbers in red. Thus the column with the red numbers should be the column for Sundays. Since the day one in the top row is in the fifth row, it should be on a Thursday, Friday should be the second, and part of a column beyond that should be Saturday the third. The unseen first Sunday should be the fourth, and then we see the fifth (Monday), the sixth (Tuesday), the seventh (Wednesday) and under the first day 1 the eight day which would be the second Thursday. The monthly calendar has only five rows for day numbers. Since there are three days in the top row the next four rows have spaces for up to twenty eight more days, thus this month can have twenty eight to thirty days total. There is an almost complete 5 in the bottom most Sunday, and then Monday the 26th, and Tuesday the 27th are visible. Thus the total number of days in the month are unknown. The next month should begin on a Thursday, Friday, Saturday, or Sunday. At the bottom left of the calendar is a fragment of a smaller monthly calendar, presumably either the previous or the next month. Careful study of the smaller calendar indicates that its day one is a Monday and its day 31 is a Wednesday, so that is consistent with the smaller calendar month being either the month before or the month after the main month on the calendar. So the main month of the calendar should be either: 1) After a 31 day month, and thus possibly be January, February, April, June, August, September, or November. or: 2) Before a 31 day month, and thus possibly be February, April, June, July, September, November, or December. But apparently the main month on the calendar can not be either March, May, or October. Memory Alpha says: https://memory-alpha.fandom.com/wiki/The_City_on_the_Edge_of_Forever_(episode) But as nearly as I can tell the main month on the calendar must either follow a 31 day month or be followed by a 31 day month. Since May is itself a 31 day month and follows April, a 30 day month, and isfollowed by June, a 30 day month, it seems that May can not be the main month on the calendar. And since May is a 31 day month, May can't be the main month on the calendar if there is a still photo or a clip showing the main month with only 30 days. In AD 1925 January and October have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1925&country=1 In AD 1926 April and July have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1926&country=1 In AD 1927 September and December have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1927&country=1 In AD 1928 March and November have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1928&country=1 In AD 1929 August has day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1929&country=1 In AD 1930 May has day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1930&country=1 In AD 1931 January and October have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1931&country=1 In AD 1932 September and December have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1932&country=1 In AD 1933 June has day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1933&country=1 In AD 1934 February, March, and November have day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1934&country=1 In AD 1935 August has day 1 on Thursday as in the photo. https://www.timeanddate.com/calendar/?year=1935&country=1 There is one other thing that I noticed about the calendar. The Sundays are marked in red, and two other days are marked in red. In the main calendar Wednesday the 14th is marked in red, and in the smaller calendar in the lower left the day I think is Tuesday the 30th is marked in red. The only holiday celebrated in the USA on the 14th I can think of is St. Valentine's Day on February 14th, an unofficial holiday. I haven't found any holidays celebrated in the USA on the 30th of any month. Thus the holiday on the 30th could be an important movable holiday like Easter of Thanksgiving. American Thanksgiving is always celebrated on a Thursday in November, while Easter is celebrated in March or April. Thus one possible theory may be that the main month in the calendar is February and the month in the lower left corner is the next month, March, when Easter is celebrated on the 30th. But Easter is always celebrated on Sunday. So possibly "The City On the Edge of Forever" happens in February 1930 EK which is the same as February AD 1935. This implies that year one EK is, or overlaps with, year AD 6. Since "The City on the Edge of Forever" was filmed in February, 1967, an actual 1967 or earlier calendar was probably used for the calendar prop. And a better picture of the calendar prop would be very useful in deciding when "The City on the Edge of Forever" actually happens.