Red Tag Sale

A “tag sale” is a retail sale where the sale items bear a colored tag. “Red tag sale” has been cited in print since at least 1888, “blue tag sale” since at least 1890 and “yellow tag sale” since at least 1890. The “red tag sale” has been the most common tag sale.
 
The earliest tag sales (in the 1890s) were conducted in furniture stores.
 
   
Wiktionary: tag sale
Noun
tag sale (plural tag sales)
1. (in combination) A retail sale in which items included in the sale are tagged with a coloured tag
2. (In the US, primarily northeastern dialects) A domestic sale of second-hand items; a garage sale or yard sale
   
(Oxford English Dictionary)
tag sale, n.
A sales promotion by a retailer during which items bearing a particular tag are sold at a reduced price. Chiefly with modifying adjective specifying the colour of the tag; esp. in red tag sale.
1891 Atlanta Constit. 22 Feb. 10 (advt.)  Their great red tag sale will be continued this week. A larger number of articles will be shown with the red tag dangling from them.
1929 Marion (Ohio) Star 24 July 11 (advt.)  Blue tag sale starting Thursday morning, July 25th… Look for the blue tags.
1977 Los Angeles Times 23 Mar. vii. 1 (advt.)  First Annual ‘Red Tag Sale’ 3 Days Only!.. ‘Red Tag’ Oldsmobiles.
 
7 October 1888, Cleveland (OH) Plain Dealer, pg. 7, col. 4 ad:
A Gigantic Sweeping Sale
FOR ONE WEEK ONLY!
“Red Tags” in Every Department.
In order to make room for an immense stock purchased in the leading furniture markets East and West to be delivered during the present month at our establishment in readiness for the fall and winter demand, we have concluded to inaugurate a “Red Tag” sale in every branch of our store.
(James Moriarty, a furniture dealer—ed.)
 
21 February 1890, The Commercial Gazette (Cincinnati, OH), pg. 8, col. 5 ad:
THE BLUE TAG
Sale we inaugurate to-day presents a bargain festival unequaled in the annals of the
FURNITURE
trade.
(Robt. Mitchell Furniture Co.—ed.)
 
29 June 1890, The Daily News (Denver, CO), pg. 12, col. 8 ad:
COOPER HAGUS FURNITURE CO.
SPECIAL RED TAG SALE OF PARLOR FURNITURE FOR THE NEXT 10 DAYS.
 
11 December 1890, Evening Express (Lock Haven, PA), pg. 4, col. 4 ad:
EVERETT & CO.
16 East Main Street.
Yellow Tag Sale of Coats.
 
Chronicling America
18 September 1891, The Columbian (Bloomsburg, PA), pg. 6, col. 4 ad:
Our red tag sale cleaned out all the old goods. New goods are continually arriving.
VOORIS & MURRAY
Largest Dealers in Furniture,
WILKES-BARRE.
 
1 May 1895, The Arizona Republican (Phoenix, AZ), pg. 8, col. 3 ad:
Our RED TAG SALE is now on.
B. HEYMAN FURNITURE CO.
 
Google Books
22 December 1897, Printers’ Ink, pg. 34, col. 1:
IN EAU CLAIRE, WIS.
EAU CLAIRE, Wis., Dec. 1, 1897.
Editor of PRINTERS’ INK:
A clothing firm recently caused to be put in all the newspapers here the words “Look out for the Red Tags,” signing no name. Later during the night the company had large red tags, with a series of special prices printed thereon, placed at each door in the city, and the next morning the papers came out with a half page announcing a “Red Tag” sale at the store.
 
Google Books
Amole One More Time
By Gene Amole
Boulder, CO: Johnson Books
1998
Pg. 17 (November 25, 1993):
But good old Thanksgiving Day remains on Thursday, like a rock. There are very few red-tag sales, doorbusters, sell-a-brations or inventory clearances on Thanksgiving Day.