The following, from critical sources (1831 and 1834, respectively) reveals that early Latter-day Saints did believe in a then-future expansion to the West as far as the Pacific Ocean:
Mormonism.—A young gentleman by the name of Whitmer,
arrived here last week from Manchester, N.Y. the seat of wonders, with a new
batch of revelations from God, as he pretended, which have just been
communicated to Joseph Smith. As far as we have been able to learn their
contents, they are a more particular description of the creation of the world,
and a history of Adam and his family, and other sketches of the anti-deluvian
world, which Moses neglected to record. But the more important part of the mission,
was to inform the brethren that the boundaries of the promised land, or the
New Jerusalem, had just been made known to Smith from God—the township of
Kirtland, a few miles west of this, is the eastern line and the Pacific
Ocean the western line; if the north and south lines have been described,
we have not learned them. Orders were also brought to the brethren to sell no
more land, but rather buy more. Joseph Smith and all his forces are to be on
here soon to take possession of the promised land. (“Mormonism,” The Painesville Telegraph 2, no. 31 [January 18, 1831]: 3, emphasis in bold added)
Their
revelation concerning the promised land, we have not been able to obtain
a copy of; it is explained, however, in the following letter from Rigdon,
written to his brethren in Ohio, soon after he became acquainted with the
movement and designs of the prophet.
"I
send you this letter by John Whitmer. Receive him, for he is a brother greatly
beloved, and an Apostle of this church. With him we send all the revelations
which we have received; for the Lord has declared unto you that you pray unto
him that Joseph Smith and myself, go speedily unto you; but at present it is
not expedient for him to send us. He has required of us, therefore, to send
unto you our beloved brother John, and with him the revelations which he has
given unto us, by which you will see the reason why we cannot come at this
time. The Lord has made known unto us, some of his great things which he has
laid up for them that love him, among which the fact (a glory of wonders it is)
that you are living on the land of promise, and that there is the place
of gathering, and from that place to the Pacific Ocean, God has
dedicated to himself, not only in time, but through eternity, as you will see
by one of the commandments, received day before yesterday. Therefore, be it
known to you, brethren, that you are dwelling on your eternal inheritance; for
which, cease not to give ceaseless glory, praise and thanksgiving to the God of
Heaven.—Yes, lift up your heads with joy, for the kingdom is ours till the
Savior comes, even so, Amen—therefore, prepare your hearts to receive salvation
which God has sent unto you, knowing that they have come from God; and know
assuredly if you receive them, you shall receive greater things, yes, things unspeakable
and full of glory—"such as eye hath not seen, nor ear heard, neither hath
it entered into the heart of man to conceive," for our God hath in visions
shown it unto me. Therefore, I write with the greatest certainty of these
things which he hath prepared for us—yes, even us, forever, who receive the revelations
of the last days, are the very people of whom the prophets spoke, and the very
saints who shall rejoice with Jesus"!!! (E. D. Howe, Mormonism
Unvailed [Painesville, Ohio: E. D. Howe, 1834], 110-11, emphasis in
bold added)
Further Reading:
Resources on Joseph Smith's Prophecies