Why "Merry Christmas"?

Yeah, it’s used a lot by folks that want to seem British, even though in reality the British don’t use it a lot. More than in the USA, I suppose.

Oh, interesting! I saw some bits and pieces of a History Channel show last night about Christmas and its traditions over the years, and it posited that “Merry” was popularized in the US because of an editorial decision to change the last line of The Night Before Christmas from “Happy Christmas to all…” to “Merry Christmas…” But it didn’t say why that change happened.

Are people seriously contending that Americans never (or almost never) say “Happy Christmas”? I find that hard to believe. The British certainly use both “merry” and “happy.” Perhaps people just notice “merry,” and its association with Christmas, more because it is a less common word, not often heard in other contexts.

Based strictly on personal experience … I would seriously contend exactly that.

There could be some regional variation (I’m from Louisiana). If so, the American media has completely ignored them.

Yes, it’s overwhelmingly “Merry Christmas.” Saying “Happy Christmas” would be jarring in the same way that saying “torch” instead of “flashlight” would be. I suppose some contrarians might do it in a vain attempt to seem clever or special, but as a general rule, in America the term “Happy Christmas” is about as common as “Merry Birthday!”

The phrase goes back to at least 1565.

"The use of ‘Merry Christmas’ as a seasonal salutation dates back to at least 1565, when it appeared in The Hereford Municipal Manuscript:

“And thus I comytt you to god, who send you a mery Christmas & many.”"

from the link below.

Yes, Americans would not say that. They would say “Merry Christmas & Happy New Year”, or “Happy Holidays”. The last is especially used in being sensitive to friends of other religions, who might be celebrating another holiday. (Nearly all religions seem to have some holiday around the calendar solstice.)