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[Detail] Discovery of the Mississippi: By Ferdinand De Soto

Historical Comprehension: Using Data from Historical Maps

Historical maps are a unique data source. They show what people knew about an area at the time the map was created. View the 16th-century Portolan Atlas. Write a caption for each image in the atlas. Then analyze images four and five, depicting North America, the Caribbean, and the Pacific Ocean.

How accurate are these early maps of North America? Find several areas of the maps that are fairly accurate. Find several that are very inaccurate. What conclusions can you draw about Europeans’ (particularly Spaniards’) knowledge of the world in 1544, when the atlas was published? Where do you think exploration most likely occurred in the second half of the 1500s?

Next, examine the mid-17th century map showing California as an island. Research the voyages of exploration of the California coast in the first half of the 16th century and the later establishment of settlements towards the end of the 17th century.

  • What might have led explorers to believe that California was an island?
  • To what extent did the mistaken belief that California was an island affect the settlement of the region?
  • What other factors contributed to the delay in settling California?
  • What prompted the Spanish to establish settlements in California in the second half of the 18th century?

Examine the 1854 map showing proposed routes of the Pacific Railroad and its branches in connection with the various systems of existing and unfinished railroads.

  • What does the map reveal about transcontinental travel?
  • How did the massive migration to California during the Gold Rush stimulate a desire for a quicker route across the continent?
  • Note the line for a proposed railway across Mexico, in a location called the Isthmus of Tehuantepec. Why would that be a good location for a railway? What issues might arise in building such a railway, given that the map of proposed railways was made by an office of the U.S. government? Try to find out if this railway was ever built and, if so, who built it.