Ah, the hanging chad! It seems just yesterday that it was on everyone’s lips, now fallen back to that obscurity whence it arose. ‘Origin unknown’ says the OED curtly, and stays not to speculate. But where the OED fears to tread folk etymology steps boldly in, with its usual flair for invention.

There is a charming folk etymology: that there was a kind of punch that made U-shaped slits rather than holes, and it had been invented by a Dr. Chadless, so chad was what a Chadless punch did not create. This is, sadly, a better example of geek humor than of word history. No one named Chadless is in the US or UK patent databases, or even in the LDS Church family history records.

From a short article by Harry R. Lewis, Gordon McKay Professor of Computer Science and Dean of Harvard College.

Chad, and chadless, first break cover in 1959 (both cites are from the same work):

J. W. FREEBODY Telegr. xi. 460/2 The small hinged discs of paper, called ‘chads’, remain attached to the body of the tape.

J. W. FREEBODY Telegr. xi. 460/2 In order..that the printed characters are completely legible, the tape is perforated by the chadless method.

One wonders if there’s a possible connection with Mr Chad, “The figure of a human head appearing above a wall, etc., with the caption ‘Wot, no - ?’, as a protest against a shortage or the like.” First cite for this is 1945:

1945 Sunday Express 2 Dec. 2/3 What is the origin of that peculiarly laughable figure called Chad we see so often scribbled across our walls?

The origin for this too is ‘obscure’, and it does seem to be a British usage whereas the former looks to be American in origin, so I suppose a connection is unlikely.  But still, hanging from a computer printout and hanging over a wall? I know, I’m reaching here, but that’s half the fun of speculation!

This “chad” is attested from 1930, as noted in Dave Wilton’s list ... referring to tape used in telegraphy.

“Chadless” can be found from 1940, and since the chadless reperforator technology seems to date from 1939 I suppose “chadless” won’t be found much earlier.

Apparently there is—or was—a [rare] surname “Chadless” ... of course entirely unrelated to the issue at hand.

The telegraphy community was international, so I don’t know that “chad” can be assumed to be distinctively or originally American.

Life of St Chad
620s: Born in Northumbria
664: Becomes abbot of Lastingham, Yorkshire
665: Chosen as bishop of Northumbria after first candidate fails to return from France
669: Archbishop of Canterbury, Theodore of Tarsus, challenges Chad’s ordination and he steps down
Late 669: Made bishop of Lichfield
672: Dies after premonition

From a BBC link which also suggests that St Chad should be made the patron saint of disputed elections.

edit from Quinion’s World Wide Words:

One curiosity of the recent debacle is that the word has moved from being what grammarians call a mass noun to a count noun. In the former you spoke of chad as a pile of stuff, but had to say piece of chad when you wanted to speak of one of the little bits; recent comments have started to speak instead of chads, where the word does refer to one item. That’s not surprising: firstly, few current users ever encountered it in its heyday, and secondly, the single bits of stuff have taken on an importance they never used to have.

I’m not so sure about the claim that it was originally a mass noun.  The earliest cites in the OED don’t support this:

1959 J. W. FREEBODY Telegr. xi. 460/2 The small hinged discs of paper, called ‘chads’, remain attached to the body of the tape. [Cited above by aldi.] 1968 J. BLACKBURN Nothing but Night vii. 64 The machines..spewed out the sixty-four-row punch cards… At the base of each machine was a vacuum tube to remove the dust and the chads.

The claim that “chad” was once exclusively uncountable is based on a few persons’ unsupported recollections only, AFAIK.

The 1930 example is ambiguous: “chad box” could mean “box for chad” or “box for chads”.

The 1938 example more-or-less equates “chad” with “chaff”, suggesting uncountability but not decisively.

The 1939 example uses the plural “chads”. Several other early examples show a plural form. I think it’s pretty sure it was countable by the 1940’s, at least sometimes. And the recollections supporting uncountability generally don’t go back that far, therefore make no contribution.