This map was published as part of a United States Geological Survey Bulletin in 1923.
It shows the "routes of the principal explorers" in the United States between 1501 and 1844.
Click on the image to view the full size map.
Though the map data was compiled in 1907, the map was published in a bulletin titled Boundaries, areas, geographic centers and altitudes of the United States and the several States with a brief record of important changes in their territory.
You can view citation information for this bulletin at the USGS Publications Warehouse.
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