Q: I recently read that the US would convert from analog to digital television “on June 12th, 2009.” I would think it is wrong to the use of the suffix “th” with a date when the year is included. In other words, it should be either “June 12th” or “June 12, 2009.” Am I correct?
A: The “th” suffix in a date – with or without the year – is unnecessary in writing even though it may be pronounced in speech. Whether it’s wrong is another matter.
This is a question of style, not grammar, and like all style issues, it’s frowned on by some and passes unnoticed by others. I’m reluctant to call it wrong, even if it is usually unnecessary.
In some writing, the author may want to put a little oomph into the date, rather than treat it as a mere statistic: “On the morning of September 11th, 2001, the sky over New York was a cloudless electric blue.”
Style guides generally require “th” in expressions like “the 12th of June” or “the 12th.” In fact, The Chicago Manual of Style (15th ed.) calls for spelling out the day when it stands alone (“the twelfth”). But the Chicago Manual doesn’t require “th” in ordinary dates.
You may wonder how we got the “th” suffix that we attach to ordinal (meaning in order or position) numbers. It originated with the ancient Indo-European suffix tos, which gave us the Old English ending tha, the Greek tos, and the Latin tus (as in sextus, for sixth).
Some stylebooks, by the way, would also prefer that when a date is given in full, the month should be abbreviated if an abbreviation is common (“Sept.” rather than “September”). Issues like these are treated differently in the various house styles of newspapers and book publishers.
Here’s a tip about dates that just about everybody can agree on:
In the month-day-year style, we use commas both before and after the year (except at the end of a sentence): “The party on March 3, 2009, was a blowout.”
But we don’t use a comma if only the day and month, or the month and year, are given: “The March 5 party was a blowout” or “The party in March 2009 was a blowout.”