1) Betsy Ross sewed the first flag.
She sits with the Founding Fathers on the Fourth of July parade float, in colonial costume, a mobcap on her head and a thirteen-star American flag draped over her knee. Most American children know her by name: Betsy Ross, the woman who sewed America’s first stars and stripes. But historians have found no definitive documentary evidence to support the story that Betsy sewed the first flag at the request of General Washington. Yes, she was a well-known seamstress in Philadelphia at that time, and she knew various members of Congress. Yes, she sewed flags. But the crucial link to this notable first, a solid piece of historical evidence, a letter, receipt, newspaper article, is missing. If she were alive today, she would likely be surprised to hear her story. Historians credit her grandson, William Canby, with manufacturing the legend in 1870. Unfortunately Mary Pickersgill, another seamstress from Philadelphia, didn’t make the history books. She sewed the Star-Spangled Banner.
2) Eli Whitney invented the cotton gin.
According to the popular story, in 1793 Eli Whitney invented the cotton gin, which successfully removed the seeds from short-fibered cotton. The machine transformed the agricultural south as cotton quickly became a profitable crop across the southern United States. Harvesting the plant remained labor intensive, and thus slave labor followed the gin. Given this story, two implications might seem obvious: first, before Mr. Whitney’s gin, people cultivating cotton around the world separated the seeds and fiber by hand, and second, prior to Whitney’s invention the British textile manufacturers relied on cotton ginned by hand. Yet these assumptions are wrong. For millennia prior to Whitney, cotton-producing cultures around the world were using something called a roller gin to remove seeds from cotton. Historical fact shows that cotton gins have been used in some form or another since the first century. Whitney invented a cotton gin.
Read more myths on Tim Grove's blog Historyplaces.