'May the 4th be with you' pun inspired annual Star Wars Day

May 4 (UPI) -- Star Wars Day, celebrated annually on May 4, started as a fan-led celebration of the science fiction franchise based on the Jedi greeting, "May the Force be with you."

The official Star Wars website said Lucasfilm historians believe the phrase "May the 4th be with you" was first used as a Fourth of July greeting in 1978, just one year after the release of the first Star Wars film, which was later retitled Star Wars Episode IV: A New Hope.

The phrase "May the 4th be with you" was used by an ad in The London Evening News in reference to May 4, 1979, the day British Prime Minister Margaret Thatcher took office.

Randy Thom, who has worked for Skywalker Sound for more than 40 years, said he came up with the pun while working as a location sound recordist during filming of the third Star Wars movie, Return of the Jedi, on May 4, 1982. Thom said he started sending annual "May the 4th Be With You" messages to the company after sharing his pun with coworkers on set.

May 4 started to become an unofficial holiday in the Star Wars fandom over the years, and Lucasfilm started officially acknowledging the holiday in the early 2010s with promoted events and Star Wars-related announcements.

The California Legislature officially declared May 4 to be Star Wars Day in 2019. The declaration was timed to coincide with the opening of Star Wars: Galaxy's Edge at Disneyland.

Other holidays and observances for May 4 include International Respect for Chickens Day, National Bike to School Day, National Candied Orange Peel Day, National Orange Juice Day and National Weather Observers Day.