Library of Congress


The Library of Congress > Teachers > Classroom Materials > Collection Connections > The American Revolution and Its Era

[Detail] An accurate map of North America.

Chronological Thinking: Examining Change over Time Using Maps

To grapple with the concept of change over time, compare an older map with a newer one of the same region (even if the maps are not rendered at exactly the same scale). For example, compare the following two maps.

The first is a 1777 map titled "The British Colonies in North America." The second is a 1785 map titled "The United States of North America, with the British and Spanish territories according to the treaty of 1784."

  • What do the two maps show?
  • What are the major differences between these two maps?
  • What differences can you see in the details presented in the maps?
  • How do these changes reflect differences between 1777 and 1785?
  • How do these changes reflect the objectives and results of the Revolutionary War?

While the changes reflected in the maps above resulted from political events, other differences between maps reflect the changing knowledge of the areas mapped. Examine the two maps below.

On a contemporary map of the United States, outline the area shown in each of the maps above. Use a different line symbol (dashed, dotted, wavy, etc.) to represent each map.

  • What geographic features are shown on both maps? According to our current knowledge, which map shows these features more accurately?
  • Which map shows more geographic features? Think of at least two possible explanations for this fact.
  • Which map shows relative distance more accurately? Use the distance between two geographic features to determine the relative accuracy.
  • Do you think the map on the left was drawn before or after 1753? Explain your reasoning.

The map on the left was, in fact, produced in 1778 and reflects additional knowledge of the area gained during the ensuing 25 years.