Wednesday, September 8th, 1976 marked the ten-year anniversary of Star Trek‘s debut on NBC. A month earlier, on Monday, August 16th, a two-hour special titled “Gene Roddenberry Presents: Star Trektennial Special” aired on station KTLA (channel 5) in Los Angeles. Hosted by Roddenberry, creator of Star Trek, the special included two episodes of the series, “Tomorrow is Yesterday” and “The City on the Edge of Forever.”
Here is the description given in the August 16th, 1976 television listings found in The Los Angeles Times (the special was one of the day’s “best bets”):
Star Trek creator Roddenberry hosts a screening of two of his favorite episodes of the series. Both represent a view of 20th-century life as seen by 23rd-century people. 
The special’s competition on the networks was coverage of the Republican National Convention. On August 20th, Cecil Smith reported that the special drew a 16.0 Nielsen rating, which was twice that of the highest-rated competing convention coverage, which was on KNBC Channel 4. Furthermore, the special drew “almost as much audience as the three networks combined” .
On September 19th, the paper’s “TV Talkback” feature had included a question about the special. Roddenberry had mentioned “meetings and fan clubs” and the writer wanted to know where he could obtain additional information; his Paramount Studios address was supplied .
I had never heard of this special before coming across it this evening. Nor can I find any reference to it anywhere (although apparently “Trektennial” was a Star Trek newsletter for a time). The special is also referred to as the “Star Trekennial.” I would be interested in knowing if a copy of this special exists somewhere. I’d like to see what Roddenberry had to say about the episodes.
On a related note, according to the television listings in The New York Times, the cast of Star Trek appeared on NBC’s The Today Show on Thursday, September 1st, 1966 . I’d love to see that.
1 Los Angeles Times. 16 Aug. 1976: E16.
2 Smith, Cecil. “GOP Average in the Ratings.” Los Angeles Times. 20 Aug. 1976: G23.
3 “TV Talkback.” Los Angeles Times. 19 Sep. 1976: S47.
4 “Television.” New York Times. 1 Sep. 1966: 55.