In 1846 in Louisville, Kentucky, John Banvard, a self-taught Missouri painter, exhibited his Three-Mile Painting, a panorama of the Mississippi and Missouri Rivers, painted from hundreds of direct observations and sketches he had executed over a period of many years along the riverbanks. The painting was exhibited by means of a giant pair of rollers upon which the canvas was wound and unwound. Following a successful run in Louisville, the exhibition drew large crowds in Boston and New York City before Banvard capped his triumph with a European tour. In a promotional description of the painting, printed in Boston in 1847 to generate interest in the exhibit, many endorsements testified to the painting's authenticity, including one signed by over one hundred captains and other officers of steamboats who had examined the painting and declared it “correct.” That authenticity and “correctness” were measures of artistic achievement testifies to the premium placed on verisimilitude in art that served as a record of discovery and observation along the American frontier.