h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

For reference, other references to THX-1138 throughout the Star Wars films include:

The order to "Send Rogues Ten and Eleven to station three-eight" in the Empire Strikes Back.
The number 1138 printed on the back of a battle droid in The Phantom Menace.
1138 appears on a digital display on the back of every Clone Trooper in Attack of the Clones, although they are supposed to be different.

It's said there's a reference in every film, but as far as I know, if one exists in Return of the Jedi, it hasn't been found.

And then there's also the factor that his audio/video digital enhancement technology is called THX.

The origin of THX-1138 is that it was the number place of Lucas' first car. Appartently.


Geggs

I can't think of any American plates that use that number system. Is Lucas not an American?

He is American, yes. I think he grew up in Modesto, where American Graffiti is set.

In that case, as he and I were growing up, then California plates were in the format nnn xxx, then around 1970 xxx nnn, then around 1985 nxxx(1/2 space)nnn, where n is a number and x is a letter. The colors and patterns have changed, too, but that's not relevant here. Numbers and letters have no geographic function, they are assigned in order of registration, so there'd be no particular likelihood that a Modesto City or Merced County resident would have a car with "THX". THX 1138 was not a possible plate until after 1985ish and it would have to be a vanity plate to have four consecutive digits (i.e. one whose identifier is one that you choose yourself and pay the state an annual fee for the privilege). There are some non-numerical symbols you can choose in a vanity plate starting in 1999, but none of these is a dash. Painting a dash in is something you might do if you were feeling risky.