The geographic limits of the purchase of Louisiana were ill-defined. Although Jefferson could rightly rejoice that Americans now controlled the entire Mississippi valley, including of course the prize of New Orleans, little else was known about what bounded the acquisition. The purchase treaty merely quoted the vague language of the Treaty of San Ildefonso, which defined Louisiana by “the Same extent that it now has in the hands of Spain, & that it had when France possessed it,” and referred to the previous transfer in ceding to the United States “the said territory with all its rights and appurtenances” (Miller, Treaties description begins Hunter Miller, ed., Treaties and Other International Acts of the United States of America, Washington, D.C., 1931-48, 8 vols. description ends , 2:499-500). In addition to the general ignorance of the unmapped areas of the far west, confusion reigned over how far east and west Louisiana extended along the Gulf Coast. Although Robert R. Livingston and James Monroe insisted in communications about the treaty that the purchase area should include West Florida as far east as the Perdido River, a critical goal of the administration, the boundaries between French and Spanish territory, as Rufus King reported to Albert Gallatin, “have never been settled by any treaty.” Spanish claims appeared stronger in Texas, but there too the French had a history of fortification and the Spanish an indifferent effort at settlement (Isaac Joslin Cox, “The Louisiana-Texas Frontier,” Quarterly of the Texas State Historical Society, 10 [1906], 1-75; Madison, Papers, Sec. of State Ser., 5:72-7; Vol. 40:301-3, 431, 433-4n; Gallatin to TJ, 18 Aug.).

During his summer sojourn at Monticello, Jefferson turned to his library for possible answers to the question of Louisiana’s boundaries. He had collected over the years a large number of English, French, and Spanish sources related to the settlement and geography of North America, and he put a portion of this collection to use in developing a historical timeline of Spanish and French efforts to settle and control Louisiana and other areas. He had clearly done much of the research by 23 Aug., when he wrote Albert Gallatin and reported his view that based on his sources, “our claim to the Perdido is solid, and to the bay of St. Bernard very argumentative.” The following day, he reported much the same to James Madison. Jefferson’s confidence in the legitimacy of American claims to St. Bernard, or Matagorda, Bay represented a shift from the more tentative assessment of the purchase area he had described in letters to John Dickinson on 9 Aug., and to Thomas Paine on the following day, although those letters also reflected his interest in an expansive reading of the purchase area. His historical sources proved to Jefferson that the United States might control not only the Mississippi and Missouri Rivers but also most of Texas and the Red and Arkansas Rivers in their entireties. This confidence reflected in large part his reliance on French sources, which not surprisingly argued in favor of French claims as opposed to Spanish ones, and his neglect of the Spanish sources in his collection. Jefferson finished his chronology by 31 Aug., when Thomas Mann Randolph copied it, perhaps for his own use as an incoming congressman. Randolph’s transcription closely followed Jefferson’s draft but did not include an extract of an early eighteenth-century French royal charter granting Antoine Crozat proprietorship over Louisiana. Either Randolph was not interested in copying the extract or Jefferson added it at a later time. In addition, Randolph streamlined much of the phrasing of the final section, which Jefferson labeled “Limits,” and excluded some quotations drawn from the work of Antoine-Simon Le Page du Pratz, one of Jefferson’s most important sources.

The president appears to have used his timeline as an aid in composing a more narrative treatment of the subject, which he entitled “An Examination into the boundaries of Louisiana” and dated 7 September. The many interlineations and long marginal notes indicate that Jefferson drafted the “Examination,” like the chronology, over several sittings. The most significant revision was a two-page insertion, the first page of which Jefferson glued on top of the penultimate page of the earlier version, thereby obscuring the original text. In addition, the president added a marginal note based on information the administration received from William C. C. Claiborne and James Wilkinson late in January 1804 (see Document II, note 10 and second authorial note; Madison, Papers, Sec. of State Ser., 6:233, 408). Jefferson may have intended the “Examination” as a general guide for American policy-making and negotiation. In a letter of 8 January 1804 to James Monroe, he reported that Madison would be sending Monroe a copy of the “Memoir” he had written on the limits of Louisiana “last summer while I was among my books at Monticello.” Monroe evidently received the document, and another transcript in a clerk’s hand ended up in the State Department’s records. Jefferson enclosed another copy in a letter of 13 March to William Dunbar, and Madison forwarded one to Livingston in a letter of 31 March (Madison, Papers, Sec. of State Ser, 6:643, 648n). Jefferson sent a fair copy in his own hand to the American Philosophical Society in December 1817 (see TJ to Peter S. Du Ponceau, 30 Dec. 1817). In that version, the historical timeline (Document I) takes up five pages of neatly composed text, and after a blank page the “Examination” (Document II) runs for twelve more, each reflecting the many revisions that Jefferson made to his original drafts.

Initially, Jefferson’s analysis ignored the question of the purchase area’s northern boundary with Canada. In January 1804, however, he turned to this subject and appended two dense pages of text to his original draft of the “Examination.” This section also appeared as a postscript in the fair copy that Jefferson sent to the APS description begins American Philosophical Society description ends and in the State Department transcript. It has not been included here because of the long time between respective compositions and because it dealt with a separate set of diplomatic issues, this time involving Great Britain rather than Spain. Both Jefferson’s historical analysis of the east and west boundaries of the purchase area and his later analysis of the northern boundary, nevertheless, reflect his desire to maximize the land area purchased from the French.