1To Thomas Jefferson from William Plumer, 1 May 1807 (Jefferson Papers)
Permit me to make my grateful acknowledgement to you for Directing the Secy of War to enclose me the Account of Lt. Pike’s voyage up the Mississippi River from St. Louis to its sourse ; which I recd a few days since. Every communication that contains facts relative to the geography, the natural, civil, & political state of our country, is to me highly useful. The last winter I had the honor of...