As an illustration of the role of scale economies in the development of cities,
consider the sewing machine, which was developed in the middle of the 19th century.
At the beginning of the century, about four-fi fths of the clothing worn in the
United States was hand-sewn in the home for members of the household, and the
rest was hand-sewn by tailors. The sewing machine (patented in 1846) allowed factories
to underprice home producers, and by 1890 nine-tenths of U.S. clothing was
being made in factories. New cities developed around the clothing factories.