“Pure As the Snow, But She Drifted” was the title of an entertainment that was printed in the Butte (MT) Miner on May 16, 1917. “‘She was as pure and as white as snow.’ ‘Yes, but she drifted.’—Yale Record” was printed in the Washburn Review (Topeka, KS) on November 30, 1921. “She was pure and white as snow; but—she drifted.—Augustana Observer” was printed in The Bethany Messenger (Lindsborg, KS) on January 28, 1922.
 
The movie Snow White and the Seven Dwarfs opened at one theater on December 21, 1937, and nationally in the United States on February 4, 1938. The column “Hollywood” by Ed Sullivan in the Sunday News (New York, NY) printed on May 1, 1938:
 
“Mae West tells vaudeville audiences: ‘I used to be Snow White, but I drifted.’”
 
Brooklyn-born actress, singer, playwright, screenwriter, comedian, and sex symbol Mae West (1893-1980) became famously associated with the “Snow White” line.
 
[This entry was assisted by prior research from the Quote Investigator.]
     
 
Wikiquote: Mae West
Mary Jane West (August 17, 1893 – November 22, 1980) was an American actress and playwright, most commonly known as “Mae” West.
(...)
I used to be Snow White, but I drifted.
. Interview in Life magazine (18 April 1969)
 
Wikipedia: Snow White and the Seven Dwarfs (1937 film)
Snow White and the Seven Dwarfs is a 1937 American animated musical fantasy film produced by Walt Disney Productions and originally released by RKO Radio Pictures. Based on the German fairy tale by the Brothers Grimm, it is the first full-length cel animated feature film and the earliest Disney animated feature film. The story was adapted by storyboard artists Dorothy Ann Blank, Richard Creedon, Merrill De Maris, Otto Englander, Earl Hurd, Dick Rickard, Ted Sears and Webb Smith. David Hand was the supervising director, while William Cottrell, Wilfred Jackson, Larry Morey, Perce Pearce, and Ben Sharpsteen directed the film’s individual sequences.
 
Snow White premiered at the Carthay Circle Theatre on December 21, 1937, followed by a nationwide release on February 4, 1938.
   
16 May 1917, Butte (MT) Miner, “Star Uncle Dick in ‘Dance of 7 Pals,’” pg. 7, col. 6:
“Pure As the Snow, But She Drifted.”
Tom McDonald…Peoples theater
   
30 November 1921, Washburn Review (Topeka, KS), pg. 3, col. 5:
“She was as pure and as white as snow.”
“Yes, but she drifted.”—Yale Record.
     
28 January 1922, The Bethany Messenger (Lindsborg, KS), pg. 2, col. 2:
She was pure and white as snow; but—she drifted.—Augustana Observer.
 
29 March 1925, Sunday American-Statesman (Austin, TX), “Campus Comedy” edited by Granville C. Dickey, pg. B2, col. 2:
SNOWDRIFT
She was pure as snow; but—she drifted.—Lyre. 
 
1 May 1938, Sunday News (New York, NY), “Hollywood” by Ed Sullivan, pg. 78, col. 3:
Mae West tells vaudeville audiences: “I used to be Snow White, but I drifted.”
     
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The 1,400 Greatest Quotes of All Time in 140 Characters or Less
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Pg. 154:
I used to be Snow White, but I drifted.
Mae West
 
OCLC WorldCat record
They used to call me Snow White ... but I drifted : women’s strategic use of humor
Author: Regina Barreca
Publisher: Lebanon, NH : University Press of New England, ©2013.
Series: Psicologia (E-libro—2014/09)
Edition/Format:   eBook : Document : English
Summary:
With a comprehensive new introduction by the author, a reissue of the influential text on women’s humor
   
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I used to be Snow White, but I drifted.- Mae West humor
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12:40 PM - 9 Jul 2019