A 3-cent violet stamp issued on September 7, 1940, commemorated the 400th anniversary of the Coronado expedition through the southwestern states. Following the Spanish conquest of the Aztecs in Mexico in the sixteenth century, and in light of the riches found there, it was assumed that similar wealth would be found in areas to the north. Coronado led two surprisingly wide-ranging expeditions, extending to the northeast as far as Kansas. Although Coronado found no great wealth, he learned about the Indians and the topography of North America. The stamp design reproduced the painting 'Coronado and His Captains' by Gerald Cassidy.