October 7, 1763 | Treaty Proclamation of 1763. In the aftermath of the French and Indian War, the British crown issued this proclamation, which severely limited colonists' access to land west of an imaginary line running down the crest of the Appalachain Mountains. With this attempt to reorganize British control in North America and maintain orderly relations with Native peoples, George III further alienated colonists who saw western expansion as an inevitable process. Many provisions in the Proclamation remained intact until 1776, although incursions by colonists into land west of the Proclamation Line were common.
March 18, 1792 | Report Thomas Jefferson to George Washington, March 18, 1792 A detailed examination of the current and future prospect for western expansion and the legal and political ramifications of such movement.
April 6, 1804 | Report William Dunbar to the American Philosophical Society, via Thomas Jefferson, read April 6, 1804. The Mississippi River, its delta, and the surrounding region receive detailed attention from William Dunbar in this report forwarded to the APS by Thomas Jefferson.