Here are several blurbs, some of which offer somewhat different twists:
BREWER’S DICTIONARY OF MODERN PHRASE & Fable (2006)
BEST THING SINCE SLICED BREAD: The best thing or person ever. A general term of commendation dating from the late 1960s and referring, tongue in cheek, to the great technological innovation that enabled bread to be wrapped and already sliced. Sliced bread was first produced in 1930, in the United States, under the brand name Wonder Bread, the bread slicing machine having been invented by Otto Rohwedder.
FACTS ON FILE DICTIONARY OF CLICHÉS (2001)
THE GREATEST THING SINCE SLICED BREAD: A useful new invention. Originating in the mid-twentieth century, probably in the armed forces, this expression also can be used sarcastically; indeed, not everyone regards packaged presliced bread as a taste treat, although it is undoubtedly a convenience. In Britain it is also put as best thing since sliced bread. . . Numerous variants have arisen, such as the greatest thing since the hamburger, chewing gum, and indoor plumbing, but none became as common as sliced bread.
SHORTER DICTIONARY OF CATCH PHRASES (1994) Compiled by R. Fergusson from the work of Eric Partridge & Paul Beale
THE BEST THING SINCE SLICED BREAD: An expression of wholehearted appreciation, often applied to a useful novelty. Used in the UK since around 1950 or earlier. The phrase may have originated in the USA in the form the greatest thing since sliced bread. It is sometimes used ironically by those who despise sliced bread as inferior convenience food.
OXFORD DICTIONARY OF IDIOMS (2005)
THE BEST (or) GREATEST THING SINCE SLICED BREAD (informal: A notable new idea, person, or thing (used to express real or ironic appreciation)
OXFORD ENGLISH DICTIONARY (1989)
. . . in colloquial phrase the best (or greatest, etc.) thing since sliced bread: an expression of enthusiastic appreciation, especially of a new invention or discovery.
Note: The OED’s quotes from the 1989 edition, in my opinion, do not provide good examples and I have not included any of them below. Their earliest quote with greatest was from 1969 and using best was from 1976. Below see my corresponding quotes from 1954 and 1957.
But the most authoritative article (includes references, notes, and very interesting details) I found – with more than everything you wanted to know about sliced bread – appeared in the often defiled Wikipedia
Note: the numbers in brackets [ ] are references and I left them in to show that the article is well-documented.
SLICED BREAD: Otto Frederick Rohwedder of Davenport, Iowa, USA invented the first loaf-at-a-time bread-slicing machine. A prototype he built in 1912 was destroyed in a fire and it was not until 1928 that Rohwedder had a fully working machine ready. The first commercial use of the machine was by the Chillicothe Baking Company of Chillicothe, Missouri, which produced their first slices on July 7, 1928. Their product, "Kleen Maid Sliced Bread", proved a success. Battle Creek, Michigan has a competing claim as the first city to sell bread presliced by Rohwedder's machine; however, historians have produced no documentation backing up Battle Creek's claim. The bread was advertised as, "the greatest forward step in the baking industry since bread was wrapped."
St. Louis baker Gustav Papendick bought Rohwedder's second bread slicer and set out to improve it by devising a way to keep the slices together at least long enough to allow the loaves to be wrapped. After failures trying rubber bands and metal pins, he settled on placing the slices into a cardboard tray. The tray aligned the slices, allowing mechanized wrapping machines to function.
W.E. Long, who promoted the Holsum Bread brand, used by various independent bakers around the country, pioneered and promoted the packaging of sliced bread beginning in 1928. In 1930 Wonder Bread, first sold in 1925, started marketing sliced bread nationwide.
The phrase "the greatest thing since sliced bread" (and variations thereof) is a commonly used hyperbolic means of praising an invention or development. Sliced bread appears to be something of an arbitrary selection as the benchmark against which later inventions should be judged. It has been said that "the phrase is the ultimate depiction of innovative achievement and American know-how", although it is commonly used in the United Kingdom as well.
The popular use of the phrase derives from the fact that Wonder Bread, the first mass-marketer of sliced bread as a product, launched a 1930s ad campaign touting the innovation.
Pre-sliced bread increased consumption of bread. While the commercially sliced bread used uniform and somewhat thinner slices, people ate more slices of bread at a time, and ate bread more frequently, because of the ease of eating another piece of bread. This increased consumption of bread and, in turn, increased consumption of spreads, such as jam, to put on the bread.
During 1943, U. S. officials imposed a short-lived ban on sliced bread as a wartime conservation measure. The ban was ordered by Claude R. Wickard who held the position of Food Administrator, and took effect on January 18, 1943. According to the New York Times, officials explained that "the ready-sliced loaf must have a heavier wrapping than an unsliced one if it is not to dry out." It was also intended to counteract a rise in the price of bread, caused by the Office of Price Administration's authorization of a ten percent increase in flour prices.
In a Sunday radio address on January 24, Mayor LaGuardia suggested that bakeries that had their own bread-slicing machines should be allowed to continue to use them, and on January 26, 1943, . .
On January 26, however, John F. Conaboy, the New York Area Supervisor of the Food Distribution Administration, warned bakeries, delicatessens, and other stores that were continuing to slice bread to stop, saying that "to protect the cooperating bakeries against the unfair competition of those who continue to slice their own bread... we are prepared to take stern measures if necessary."
On March 8, 1943, the ban was rescinded. Wickard stated that "Our experience with the order, however, leads us to believe that the savings are not as much as we expected, and the War Production Board.
A ban on sliced bread, that’s rich!
The following are quotes from archived sources:
(quotes from archived sources)<1952 “‘Don’t worry about television,’ Red Skelton advises in a recent interview. ‘It’s the greatest thing since sliced bread.’”—Sallisbury Times (Maryland), 5 January, page 10> [[archived source]]
<1954 “We Kokomons think that our memorial Gymnasium is about the best thing since sliced bread”—Kokomo Tribune (Indiana), 16 December, page 16>
<1957 (advertisement) “The Greatest Thing Since Sliced BREAD: Ford V-8 Rebuilt Motor – All new parts guarantee – Models ’32 through ’53 – $99.50”—Star-News (Pasadena, California), page 28>
<1971 “. . . I’ve got my arm around her, telling her she’s the greatest thing since sliced bread.”—News and Tribune (Jefferson City, Missouri), 23 May, page 26>
<1982 “A start-up problem [[with]] the UH-60 Black Hawk helicopter does not diminish the fact that it’s ‘the best thing since sliced bread for Army aviators,’ . . . “—European Stars and Striped (Damstadt, Germany), 2 April, page 8>
<1991 “Your mom is looking at you like you were the best thing since sliced bread and making plans for you to have a modeling contract and grad school diploma by age 5.”— Syracuse Herald Journal (New York), 10 May, page 198>
<1997 “He called and we have gone out twice. I like him, but I don't consider him the greatest thing since sliced bread.”—Frederick News-Post, 14 March, page 24>
<2005 “. . .was struck by an odd sight in her neighbor's driveway, an apparent apparition from the past: a dairy truck delivering milk to a box on the front porch. Upon investigation, she signed up for the service herself. ‘It's the best thing since sliced bread,'' she said.”—New York Times, 23 January>
< 2010 “The vast majority of candidates believe they are good at this and good at that. What they need to say is ‘I am the greatest thing since sliced bread at this . . . ’ but are often afraid to do so because they feel it may cut them off from other opportunities.”—Evening Standard (London), 11 May>
From my observation of the above quotes and the many I didn’t list, it appears that in the U.K. the preferred form is BEST THING SINCE SLICED BREAD. However, in the U.S. BEST and GREATEST seem to be used interchangeably. Personally, I tend to use GREATEST.
Ken G – June 19, 2010