The story has already been told of the entrance of the United States into the question as a third claimant, through Gray's discovery, the Louisiana Purchase, and the Lewis and Clark expedition. The story of how the United States succeeded to the modified claim of Spain to the Oregon region belongs to the sequel of the Louisiana Purchase. The purchase of Louisiana left the United States with a group of intricate and delicate questions to settle with Spain, and with Spain in no mood for a speedy and amicable settlement. The transfer of Louisiana had not carried with it a clear definition of its boundaries. This was in part true of its boundary on the east, and especially true of its western boundary. Almost immediately on the transfer of the territory negotiations were begun with Spain on questions arising out of the transfer, or intimately connected with it. Two main objects of the negotiations on the part of the United States were, to secure from Spain, by purchase or otherwise, the cession of her remaining possessions east of the Mississippi, and the settlement of the boundary of Louisiana to the west. Any question in respect to the Oregon country seems not at first to have been present to the thought of either party. Negotiations were begun in 1804, and were continued, with intervals of interruption, until February 22, 1819, when, by a convention of that date, the Floridas were ceded by Spain to the United States, and a boundary line west of the Mississippi agreed upon. This western boundary line, after striking latitude 42° near the supposed source of the Arkansas River, was to run west on this parallel to the Pacific Ocean. Article III of this convention, after particularly describing this line, concludes: "The two high contracting parties agree to cede and renounce all their rights, claims, and pretensions to the territories described by said line: That is to say, the United States hereby cede to his Catholic Majesty, and renounce forever all their rights, claims, and pretensions to the territories lying west and south of the above described line; and, in like manner, his Catholic Majesty cedes to the United States all his rights, claims, and pretensions to any territories east and north of the said line; and for himself, his heirs, and successors renounces all claim to the said territories forever." Thus the Florida treaty, though making no mention of the Oregon Territory, incidentally carried with it the final delimitation of that territory on the south, and the transfer to the United States of the Spanish claim to Oregon. By this treaty the earliest claimant to the Oregon Territory ceased longer to be a party to the question of its sovereignty.