RC (DLC); misdated and corrected by TJ both on the letter and in SJL entry; addressed: “Mr. Jefferson”; endorsed as received 27 Aug. 1790 and so recorded in SJL.

For six years TJ and Washington had corresponded about the great object of tapping the “source of wealth and power … from the Western country” by way of the Potomac and Ohio rivers to Lake Erie (TJ to Washington, 15 Mch. 1784; Washington to TJ, 1 Jan. 1788; see also Madison to TJ, 9 Jan. 1785). Now the threat of war between Spain and England, the increasing impatience of the western inhabitants at the closure of the Mississippi, the growing danger that disaffected persons in that region would look to England or to Spain for the securing of their vital interests, the decision to locate the permanent residence of government on the Potomac, the restiveness of the Indians in the Northwest, and the rumors of military preparations in Detroit for a possible descent on Spanish territory—all of these public and some private interests brought the subject again to the fore. The journey to Rhode Island offered perhaps the first opportunity the two men had had in some years to discuss the results of Washington’s various efforts to procure information about navigation to Lake Erie (see Washington to Richard Butler, 26 Nov. 1786 and 10 Jan. 1788; to William Irvine, 10 Jan. and 31 Oct. 1788, Writings, ed. Fitzpatrick, Writings, xxix, 89, 369–71; xxx, 123; Freeman, Washington description begins Douglas Southall Freeman, George Washington, N.Y., 1948–1957, 6 vols.; 7th volume by J. A. Carroll and M. W. Ashworth, New York, 1957 description ends , vi, 23–6). Immediately on their return Washington’s first business was connected with such information, but with military not commercial objectives—that of planning the expedition against the Indians (see note, TJ’s second opinion, 29 Aug. 1790, Document xi in group of documents on the war crisis).

Washington and TJ had also long been interested in the approach to Lake Erie by way of the Big Beaver creek; the latter looked forward to the improvement of the navigation of the Potomac and the Ohio and to the junction of the Big Beaver and the Cuyahoga by canal as likely to “spread the feild of our commerce … Westwardly … beyond any thing ever yet done by man” (TJ to Madison, 8 Dec. 1784; TJ to Washington, 6 Apr. 1784). In DLC: TJ Papers, 56: 9541, attached to Rittenhouse to TJ, 2 July 1790, there is a leaf of notes in Rittenhouse’s hand giving the boundaries of Pennsylvania, with particular distances and locations of intersections of the western boundary with Little Beaver creek and with the branches of Big Beaver. But it is unlikely that TJ received this document in 1790, for it seems to belong to the period 1786–1787 when he was engaged in revising the map for Notes on Virginia and was urgently requesting information about the western boundary (see TJ to Page, 4 May 1786; TJ to Hopkinson, 14 Aug. 1786; see also Rittenhouse to TJ, 28 Sep. 1785 and 8 Nov. 1788).