The Oxford English DIctinary, 2nd Edition, the definitive resource for English etymologies and definitions, states:
“28. a. A barrier or counter, over which drink (or food) is served out to customers, in an inn, hotel, or tavern, and hence, in a coffee-house, at a railway-station, etc.; also, the space behind this barrier, and sometimes the whole apartment containing it.
1592 Greene Art Conny Catch. iii. 20 He was acquainted with one of the seruants…of whom he could haue two pennyworth of Rose-water for a peny…wherefore he would step to the barre vnto him.
1601 Shakes. Twel. N. i. iii. 74 Bring your hand to’th Buttry barre, and let it drinke.
1712 Addison Spect. No. 403 _9, * laid down my Penny at the Barr…and made the best of my way to Cheapside.
1835 Marryat Jac. Faith. xii, He sees the girl in the bar.
1837 Hawthorne Amer. Note-bks. (1871) I. 42 A bottle of champagne was quaffed at the bar.”
Dwight
Apparently, Lileth just put down the date of the origin of Webster’s definition 1) of bar (a relatively long, evenly shaped piece of some solid substance, such as wood, or an oblong piece of any material) and didn’t bother to think that the origin of definition 6) of bar (counter or place where beverages, esp. liquors or light foods, are served to customers) might be hundreds of years later. This is obviously wrong.
I don’t know who Lileth is: a search comes up with no posts under that name. I guess she’s been disappeared, presumably after someone knowledgeable read her staff reports.
We can only hope the same for some of the other posters here… 
bar stool: what Davy Crockett stepped in.
That Staff Report was written a very, very lonnnnnng time ago. We didn’t have the same standards or editing that we have had for the last many years.
Lileth is long gone from the SDSAB, I’ll see if I can get someone to reexamine and fix the old report. Failing that, we might “disappear” it for a while. Thanks for finding this.
Hey, give the kid a break. He was only three when he killed himself a b’ar. At that age, he was probably still stepping in his own stool. 
From http://www.etymonline.com/index.php?search=bar&searchmode=none
A great resource but not perfect of course.
bar (2)
“tavern,” 1592, from the bars of the barrier or counter over which drinks or food were served to customers (see bar (1)). Barmaid is from 1772; bar-tender is 1836, Amer.Eng.; barfly “habitual drunkard” is from 1910.
Jim
And for those who want more, English supposedly picked it up from Medieval Latin barra, of uncertain etymology. (Some camps favor Gaulish barros, “head, end” or its other Celtic cognates, and some favor Old Norse barr, “conifer, pine needles, tree,” or its unattested-but-presumed Old English cognate.) I can see the semantic pine tree > thing made of pine tree > modern meanings.