A page proof came back to me last night with this sentence marked: "A freight train smacked into a truck carrying garbage and careened off the tracks in Rosedale Tuesday afternoon, triggering an explosion felt throughout the region and sending up a plume of black smoke visible for miles." The suggestion was to change careened to careered.
I went into the careen/career distinction once in my copy editing class, and got even blanker looks than usual.*
We used to be quite firm about this. Theodore Bernstein in The Careful Writer (1965) and John Bremner in Words on Words (1980) were emphatic: To career is to move forward recklessly and at speed; to hurtle. To careen means to sway from side to side, or to heel over. Readers of C.S. Forester's Hornblower series will recall that to careen a ship is to beach it and tilt it on its side in an informal dry dock to clear off barnacles and make repairs. (The word comes from carina, Latin for the keel of a ship.)
Merriam-Webster's Dictionary of English Usage (1994) suggests that the problem is that the motion being described may incorporate both high speed and swaying, so that for many writers the words are functionally equivalent. MWDEU also suggests that the wider sense of careen may be a U.S. rather than a British usage.
Bryan Garner remains old-school on this point, saying that American writers for the past century have been trying to make careen do the work of career, but "the most careful writers reserve career" for the sense of moving wildly and at speed. But his Language-Change Index in Garner's Modern American Usage (2009) for careen is stage 4: "Ubiquitous but ..." Canute sensing the incoming tide.
For what it's worth, and it's not much, the Associated Press Stylebook doesn't appear to care, having abandoned the distinction long since or perhaps never having considered it at all; the oldest copy in my possession, the 1986 edition I was issued when I started at The Sun, is silent on the subject.
My own sense, pace Messrs. Bernstein, Bremner, and Garner, is that the careen/careen distinction is so long eroded, and career as a verb so unfamiliar to most American readers, that maintaining the distinction today serves no useful purpose in editing.
But you wonder, perhaps, what I did about that marked proof? Well, we didn't know exactly how fast the train was going, but we do know that several cars derailed and heeled over on their sides, careening in precisely the original sense.