Yes, it's the age-old, not-really-that-important, but fascinating nonetheless, question of how to spell Theatre. Or Theater. And what does your spelling choice say about who you are? Hm...
A common thought of these spellings is simply that "theatre" is the British spelling of that dramatic word, whereas "theater" is the American word, like a host of other American vs. British spellings, and it's been that way for generations. Center and Centre. Color and colour. But "color" and "center" were also sometimes used in British English, and English was wildly and widely inconsistent in spellings for centuries... Yes, we started nailing things down with dictionaries a few hundred years ago, and yes, there actually are reasons why spelling has developed as it has, having to do with entomology and phonetics--which is intriguing but lengthy and not necessary to delve into here! But in terms of this one word, theatre/theater--it's not actually an old British vs. American word.
Apparently, the "re" spelling was used pretty much throughout Britain and the United States until the last 50 years or so. Rob Weinert-Kendt wrote a recent article in American Theatre where he explains:
The etymology, if we must go there, is that “theatre” has been the accepted English spelling since roughly the 17th century, deriving from the French, in turn deriving from the Greek (“theatron”), while “theater” is a relatively recent American revival of an old Middle English spelling.
Okay, so what's the difference? Is theatre for the stage and theater for showing movies? Is a theater the venue and theatre the art? We could look at these stats from Grammatist.com:
Searching a selection of 40 American news and cultural publications that put their content online, theaters appears 8,500 times from 2000 to the present, against just under 200 instances of theatres. This just suggests that theater is the preferred spelling for actual venues (the art form is a mass noun so would only rarely be pluralized), which no one seems to dispute. What’s more interesting is that the phrase theater critic appears 260 times against three instances of theatre critic, theater actor appears 43 times against zero instances of theatre actor, theater scene appears 60 times against two instances of theatre scene, and the phrase contemporary theater appears 27 times against two instances of contemporary theatre (and both of these are in names of buildings).
Still--what's the connotation for a theatre or theater company? And does it matter? Does "re" sound more pretentious and foreign? Is "er" a spelling more modern or inclusive for the "everyday" person? Or is "re" cool and youthful and worldly? Is "er" more xenophobic and stale? Can they both have both connotations? Why do founding artistic directors choose the spellings that they do? I know a few, and could ask a few, but for now, let's just look at the stat Weinert-Kendt points out: "Of the 511 member theatres listed here [Members of TCG] which use the word in their name, just 87 spell it “theater,” with a whopping 242 continuing with “theatre.”
So who knows. Let's just hope no one is judging a theatre/er company by its spelling. Because a whole lot of theatre companies and theater companies are putting out some meaningful and inspiring theatre and theater. Maybe a spelling is just a spelling. And a forever theater, or theatre, ice-breaker.