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Elizabeth Zimmermann (August 9, 1910 – November 30, 1999) was a British-born knitter known for revolutionizing the modern practice of knitting through her books and instructional series on American public television.
Though knitting back and forth on rigid straight needles was the norm, she advocated knitting in the round using flexible circular needles to produce seamless garments and to make it easier to knit intricate patterns. She also advocated the Continental knitting method, claiming that it is the most efficient and quickest way to knit. During World War II, German or continental knitting fell out of favor in the UK and US due to its association with Germany. Many English-language books on knitting are in the English or American style. Elizabeth Zimmermann helped to re-introduce continental style knitting to the United States.
Born in England as Elizabeth Lloyd-Jones, she attended art schools in Switzerland and Germany. Her autobiographical "Digressions" in the book Knitting Around reprinted many of her original artworks alongside the text. Zimmermann learned to knit first from her mother and aunts (English Style) and then later from her Swiss governess (German or Continental Style).
Zimmerman eventually migrated to the United States with her new husband, German brewery master Arnold Zimmermann. The Zimmermanns initially settled in New York and eventually moved across country, finally settling in Wisconsin in a converted schoolhouse which would become home to Schoolhouse Press, a mail-order knitting business still based in the schoolhouse and run by her daughter Meg Swansen.
Zimmermann is credited with knitting the first example of an Aran sweater seen in an American magazine (Vogue Knitting). (While it may have been the first item knitted, another pattern had been published 2 years previously. The pattern for which Zimmerman knitted the model was published in Vogue Pattern Book in 1958, while a collection of patterns for men's and women's Aran sweaters with matching socks and mittens, entitled "Hand Knits from the Aran Islands," was published in a 1956 issue of Woman's Day Magazine.)
According to her posthumously published book The Opinionated Knitter, a yarn-company editor altered Zimmermann's circular knitting instructions for a Fair Isle Yoke pullover after she submitted the sweater, rendering it in the back-and-forth "flat" knitting method that was more popular among American knitters at the time. This alteration led Zimmermann to begin to publish her own instructions as Wool Gatherings.
Zimmermann's PBS knitting series is still available on VHS and DVD. In one episode, a police officer (and friend of the family) pulled Zimmermann and her husband over for "knitting without a license." (Always knitting, she'd even developed the ability to knit while on the back of her husband's motorcycle.) In The Opinionated Knitter, Zimmermann's daughter Meg notes that while her mother wanted to call her first book The Opinionated Knitter, her publishers changed it to Knitting Without Tears. However, the former perhaps best expresses Zimmermann's knitting philosophy. In all her published works (print and video), she encouraged knitters to experiment and develop their own patterns and ideas, letting their latent creativity unfold.
Her "EPS" (Elizabeth's Percentage System) is still widely used by designers: it consists of a mathematical formula to determine how many stitches to cast on for a sweater, given that the sleeves and body are usually proportionate no matter what yarn or gauge is used.
Other patterns and techniques for which she is well known are the so-called "Pi Shawl," a circular shawl that Zimmermann claimed was formed by regularly spaced increases based on Pi -- as she said in her book Knitter's Almanac, "the geometry of the circle hing[es] on the mysterious relationship of the circumference of a circle to its radius. A circle will double its circumference in infinitely themselves-doubling distances, or, in knitters' terms, the distance between the increase-rounds, in which you double the number of stitches, goes 3, 6, 12, 24 and so on." The shawl is not, however, based on Pi in any special way, but only on the property common to all two-dimensional shapes in Euclidean geometry that all dimensions increase by the same factor at the same rate; the circular shape is simply created by regularly spacing the increases). Zimmermann is also known for the "i-cord" (or "idiot cord"), and the "Baby Surprise Jacket," which is knitted completely flat and then folded, origami-style, to create a shaped jacket.
She also founded a series of Knitting Camps that continue to this day under her daughter's direction.
In her obituary, The New York Times wrote, "Mrs. Zimmermann chose to play down her influence on knitting, coining the term unventions for her woolly inventions." 
Zimmermann was the first knitter to be honored with a full obituary and article in the New York Times titled "E. Zimmermann Is Dead at 89; Revolutionized Art of Knitting." It appeared on Sunday, December 12, 1999. Her motto was: "Knit on with confidence and hope, through all crises."
- Martin, Douglas (1999-12-12). "E. Zimmermann Is Dead at 89; Revolutionized Art of Knitting". New York Times. Retrieved 2011-10-17.
- Martin, Douglas (December 12, 1999). "E. Zimmermann Is Dead at 89; Revolutionized Art of Knitting". The New York Times.
- Zimmermann, Elizabeth (1971). Knitting Without Tears (1995 Fireside paperback ed.). New York: Simon & Schuster. ISBN 0-684-13505-1. OCLC 475746806.
- Zimmermann, Elizabeth (1974). Knitter's Almanac (1981 Dover paperback ed.). New York: Dover Publications. ISBN 0-486-24178-5. OCLC 851977417.
- Zimmermann, Elizabeth (December 1, 1981). Knitting Workshop. Wisconsin: Schoolhouse Press. ISBN 0-942018-00-1.
- Zimmermann, Elizabeth (June 1, 1989). Knitting Around (June 2001 reprint ed.). Wisconsin: Schoolhouse Press. ISBN 0-942018-03-6.
- Zimmermann, Elizabeth (January 30, 2005). The Opinionated Knitter: Elizabeth Zimmermann Newsletters 1958-1968. Wisconsin: Schoolhouse Press. ISBN 0-942018-26-5.
- Schoolhouse Press Started by Elizabeth Zimmermann in 1958
- Remembering Elizabeth... from Knitting Universe Magazine
- The Influence of Elizabeth Zimmermann and School House Press An online catalog of the University of Wisconsin Design Center October 2006 Exhibition.
- Elizabeth Zimmermann: A Tribute to 50 Years of Inspiration at Vogue Knitting