Joseph Smith's article titled "Church History," commonly referred to as the Wentworth letter, was published in the Times and Seasons in March, 1842.
As explained in the Historical Introduction, the Wentworth letter appears to borrow considerable material from a pamphlet published by Orson Pratt in 1840. (Orson Pratt in turn had borrowed from Oliver Cowdery's Letters VII and VIII.)
The Joseph Smith Papers published Pratt's pamphlet and shaded parts of the text that correspond to the Wentworth letter.
Orson Pratt's pamphlet set out at length his hemispheric theory of Book of Mormon geography, with Lehi landing in Chile, Mulek landing in North America, etc.
By comparing the two documents, it is apparent that Joseph Smith made several minor but significant changes/corrections. One of the most important is that Joseph replaced Pratt's hemispheric model with the simple declaration that "The remnant are the Indians that now inhabit this country."
Joseph's statement is consistent with D&C 28, 30 and 32, the New York Cumorah, the "plains of the Nephites" in Ohio, Indiana and Illinois, etc.
By contrast, Orson Pratt's hemispheric model was based on pure speculation that Joseph never endorsed and instead explicitly replaced in the Wentworth letter.
Here's what Pratt had written about his hemispheric model.
The remaining remnant, having dwindled into an uncivilized state, still continue to inhabit the land, although divided into a “multitude of nations,” and are called by Europeans the “American Indians.”
We learn from this very ancient history, that at the confusion of languages, when the Lord scattered the people upon all the face of the earth, the Jaredites, being a righteous people, obtained favour in the sight of the Lord, and were not confounded. And because of their righteousness, the Lord miraculously led them from the tower to the great ocean, where they were commanded to build vessels, in which they were marvellously brought across the great deep to the shores of North America.
And the Lord God promised to give them America, which was a very choice land in his sight, for an inheritance. And He swore unto them in his wrath, that whoso should possess this land of promise, from that time henceforth and forever, should serve him, the true and only God, or they should be swept off when the fulness of his wrath should come upon them, and they were fully ripened in iniquity. Moreover, he promised to make them a great and powerful nation, so that there should be no greater nation upon all the face of the earth.
Accordingly, in process of time, they became a very numerous and powerful people, occupying principally North America; building large cities in all quarters of the land; being a civilized and enlightened nation. Agriculture and machinery were carried on to a great extent. Commercial and manufacturing business flourished on every hand; yet, in consequence of wickedness, they were often visited with terrible judgments. Many prophets were raised up among them from generation to generation, who testified against the wickedness of the people, and prophesied of judgments and calamities which awaited them, if they did not repent, &c. Sometimes they were visited by pestilence and plagues, and sometimes by famine and war, until at length (having occupied the land some fifteen or [p. 15] sixteen hundred years) their wickedness became so great, that the Lord threatened, by the mouth of his prophets, to utterly destroy them from the face of the land. But they gave no heed to these warnings; therefore the word of the Lord was fulfilled; and they were entirely destroyed; leaving their houses, their cities, and their land desolate; and their sacred records also, which were kept on gold plates, were left by one of their last prophets whose name was Ether, in such a situation, that they were discovered by the remnant of Joseph, who soon afterwards were brought from Jerusalem to inherit the land.
This remnant of Joseph were also led in a miraculous manner from Jerusalem, in the first year of the reign of Zedekiah, king of Judah. They were first led to the eastern borders of the Red Sea; then they journeyed for some time along the borders thereof, nearly in a south-east direction; after which, they altered their course nearly eastward, until they came to the great waters, where, by the commandment of God, they built a vessel, in which they were safely brought across the great Pacific ocean, and landed upon the western coast of South America.
In the eleventh year of the reign of Zedekiah, at the time the Jews were carried away captive into Babylon, another remnant were brought out of Jerusalem; some of whom were descendants of Judah. They landed in North America; soon after which they emigrated into the northern parts of South America, at which place they were discovered by the remnant of Joseph, something like four hundred years after.
From these ancient records, we learn, that this remnant of Joseph, soon after they landed, separated themselves into two distinct nations. This division was caused by a certain portion of them being greatly persecuted, because of their righteousness, by the remainder. The persecuted nation emigrated towards the northern parts of South America, leaving the wicked nation in possession of the middle and southern parts of the same. The former were called Nephites, being led by a prophet whose name was Nephi. The latter were called Lamanites, being led by a very wicked man whose name was Laman. The Nephites had in their possession a copy of the Holy Scriptures, viz. the five books of Moses, and the prophecies of the holy [p. 16] prophets, down to Jeremiah, in whose days they left Jerusalem. These Scriptures were engraved on plates of brass, in the Egyptian language.15 They themselves also made plates, soon after their landing, on which they began to engrave their own history, prophecies, visions, and revelations. All these sacred records were kept by holy and righteous men, who were inspired by the Holy Ghost; and were carefully preserved and handed down from generation to generation.
And the Lord gave unto them the whole continent, for a land of promise, and he promised, that they, and their children after them, should inherit it, on condition of their obedience to his commandments; but if they were disobedient, they should be cut off from his presence. And the Nephites began to prosper in the land, according to their righteousness, and they multiplied and spread forth to the east, and west, and north; building large villages, and cities, and synagogues, and temples, together with forts, and towers, and fortifications, to defend themselves against their enemies. And they cultivated the earth, and raised various kinds of grain in abundance. They also raised numerous flocks of domestic animals, and became a very wealthy people; having in abundance gold, silver, copper, tin, iron, &c. Arts and sciences flourished to a great extent. Various kinds of machinery were in use. Cloths, of various kinds, were manufactured. Swords, cimeters, axes, and various implements of war were made, together with head-shields, arm-shields, and breastplates, to defend themselves in battle with their enemies. And in the days of their righteousness, they were a civilized, enlightened, and happy people.
But, on the other hand, the Lamanites, because of the hardness of their hearts, brought down many judgments upon their own heads; nevertheless, they were not destroyed as a nation; but the Lord God sent forth a curse upon them, and they became a dark, loathsome, and filthy people. Before their rebellion, they were white and exceedingly fair, like the Nephites; but the Lord God cursed them in their complexions, and they were changed to a dark colour; and they became a wild, savage, and ferocious people; being great enemies to the Nephites, whom they sought, by every means, to destroy, and many times came [p. 17] against them, with their numerous hosts to battle, but were repulsed by the Nephites, and driven back to their own possessions, not, however, generally speaking, without great loss on both sides; for tens of thousands were very frequently slain, after which they were piled together in great heaps upon the face of the ground, and covered with a shallow covering of earth, which will satisfactorily account for those ancient mounds, filled with human bones, so numerous at the present day, both in North and South America.
The second colony, which left Jerusalem eleven years after the remnant of Joseph left that city, landed in North America, and emigrated from thence, to the northern parts of South America; and about four hundred years after, they were discovered by the Nephites, as we stated in the foregoing.
They were called the people of Zarahemla. They had been perplexed with many wars among themselves; and having brought no records with them, their language had become corrupted, and they denied the being of God; and at the time they were discovered by the Nephites they were very numerous, and only in a partial state of civilization; but the Nephites united with them, and taught them the Holy Scriptures, and they were restored to civilization, and became one nation with them.16 And in process of time, the Nephites began to build ships near the Isthmus of Darien, and launch them forth into the western ocean, in which great numbers sailed a great distance to the northward, and began to colonize North America.17 Other colonies emigrated by land, and in a few centuries the whole continent became peopled. North America, at that time, was almost entirely destitute of timber, it having been cut off by the more ancient race, who came from the great tower, at the confusion of languages; but the Nephites became very skilful in building houses of cement; also, much timber was carried by the way of shipping from South to North America. They also planted groves and began to raise timber, that in time their wants might be supplied. Large cities were built in various parts of the continent, both among the Lamanites and Nephites. The law of Moses was observed by the latter. Numerous prophets were raised up from time to time throughout their generations. [p. 18] Many records, both historical and prophetical, which were of great size, were kept among them; some on plates of gold and other metals, and some on other materials. The sacred records, also, of the more ancient race who had been destroyed, were found by them. These were engraved on plates of gold. They translated them into their own language by the gift and power of God, through the means of the Urim and Thummim. They contained an historical account from the creation down to the Tower of Babel, and from that time down until they were destroyed, comprising a period of about thirty-four hundred, or thirty-five hundred years. They also contained many prophecies, great and marvellous, reaching forward to the final end and consummation of all things, and the creation of the new heaven and new earth.
For a table that compares key parts of the two documents, go to: