Over the last decade or more, what used to be the standard manner of referring to events in the past by designating their dates in a prepositional phrase is being replaced by a longer form whereby the word back is inserted before the preposition regardless of the proximity of the past event to the speech event. Here are some recent examples:
(1) “There was a moment back in 2002 when . . . [opening sentence]” (Caryn James, “Aniston Agonistes: Good Girl, Bad Choices,” The New York Times [henceforth NYT], 6/5/06, p. B1);
(2) “The author of seven other books, she was a fellow at the library when she first got the idea back in 2001, on 9/11″ (Patricia Cohen, NYT, 2/14/08, p. B9);
(3) “back in January” – said in February (unidentified man, viva voce; cf. [way] back [when]).
(4) “Back in the seventeenth century, the original text had been registered for publication as” (Jonathan Bate, Soul of the Age (New York: Random House, 2009], p. 341)
The last is a particularly telling example. The context is entirely localized temporally in the seventeenth century, i. e., all the events are dated to that time, making the use of the word back utterly otiose. Moreover, it is from a contemporary British author (a university professor at that), showing that this linguistic feature has taken hold cisatlantically.
One hears such examples constantly on the radio and from ordinary speakers; moreover, the preposition in question can be on or during as well as in (back on Thursday, back during the war). And whereas the appearance of back was formerly conditioned strictly by the remoteness of the past event relative to the speech event––a form of emphasis––now the emphatic meaning is apparently being neutralized: the appearance of back is becoming obligatory regardless of the degree of proximity of the past event.
How to explain this development? One more or less speculative explanation comes to mind.
This new––habitual but redundant––use of the locative adverb back with designators of time could be motivated by what might be labeled the avoidance of placeless existence. A past event is by definition no longer existent in the same sense as a present event. This fundamental “non-is-ness” of a past event makes its designation unstable, and thereby in need of extra temporal determination. The most routine way in which all languages fix or anchor time expressions, with their quintessential instability, is by localizing them through the use of words denoting space. Accordingly, the near-obligatory extension to non-emphatic contexts of the emphatic word back before prepositional phrases as a designator of remoteness in time in contemporary American speech may be yet another example of what is clearly a general grammatical tendency.