To the Senate of the United States:
Most of the Indians residing within our northern boundary on this side of the Mississippi receiving from us annual aids in money and necessaries, it was a subject of complaint with the Sacs that they received nothing and were connected with us by no treaty. As they owned the country in the neighborhood of our settlements of Kaskaskia and St. Louis, it was thought expedient to engage their friendship, and Governor Harrison was accordingly instructed in June last to propose to them an annuity of $500 or $600, stipulating in return an adequate cession of territory and an exact definition of boundaries. The Sacs and Foxes acting generally as one nation, and coming forward together, he found it necessary to add an annuity for the latter tribe also, enlarging proportionably the cession of territory, which was accordingly done by the treaty now communicated, of November the 3d, with those two tribes.
This cession, giving us a perfect title to such a breadth of country on the eastern side of the Mississippi, with a command of the Ouisconsin, strengthens our means of retaining exclusive commerce with the Indians on the western side of the Mississippi--a right indispensable to the policy of governing those Indians by commerce rather than by arms.
The treaty is now submitted to the Senate for their advice and consent.
Thomas Jefferson, Special Message Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/203609