That's not technically true, although it's easy to believe because the LDS church continues to make similar statements.
At the very least if you're going to comment on the end of polygamy in the LDS church you should do some research. Perhaps read Michael D. Quinn's LDS Church Authority and New Plural Marriages, 1890 - 1904, here as printed in Dialogue, a Journal of Mormon Thought and written while he was a Professor of History at BYU. Although this paper resulted in Dr. Quinn's excommunication (under the doctrine made famous by Apostle Boyd K. Packer as "faithful history" or "faith-promoting history"), its truth was later admitted by LDS Apostle Dallin H. Oaks and countless other LDS and non-LDS historians, including Todd Compton.
1911 is probably a better date to use as the year that the LDS church officially banned new polygamy.
Some notes:
First, the 1890 Manifesto (and the Second Manifesto, in 1904) applied to new polygamous marriages and did not affect existing polygamous marriages. Even though those marriages were illegal under the laws that permitted Utah to become a state, it makes sense. If a man had four (or forty) wives, I'd say it wasn't humane to force him to abandon all but one of his families.
As LDS Apostle Dallin H. Oaks wrote:
"It is also clear that polygamy did not end suddenly with the 1890 Manifesto. Polygamous relationships sealed before that revelation was announced continued for a generation. The performance of polygamous marriages also continued for a time outside the United States, where the application of the Manifesto was uncertain for a season. It appears that polygamous marriages also continued for about a decade in some other areas among leaders and members who took license for the ambiguities and pressures created by this high-level collision between resented laws and reverenced doctrines."
Dallin H. Oaks, Gospel Teachings About Lying.
So mainstream LDS polygamous marriages performed before the Manifesto continued to exist as polygamous marriages into the 1940's and 1950's.
Second, somewhere between 200 and 2,000 polygamous marriages were performed after the 1890 Manifesto (the 200 figure is an early figure; new researchers continue to find additional marriage records and the figure now seems to be above 2,000). The First Presidency performed marriages in Mexico (even though polygamy was illegal in Mexico) and onboard U.S.-flagged ocean vessels (although the U.S. Constitution and statutory law had already extended the jurisdiction of federal law, and therefore all anti-polygamy laws, to any persons and activities aboard U.S. vessels traveling on the high seas). Two Apostles personally performed post-Manifesto marriages and nearly every member of the First Presidency sanctioned or participated in a post-Manifesto polygamous marriage. At least one Apostle entered into a polygamous marriage post-Manifesto.
You can look it up. I'll be happy to find and post multiple sources, including LDS historian-sources, in return for a donation to the Boy Scouts of America.
As Todd Compton, LDS polygamy researcher (and LDS member, and recent winner of the Best Mormon Book Award for In Sacred Loneliness: The Plural Wives of Joseph Smith) stated in 2007 about post-Manifesto marriages:
Giving up polygamy was not easy for the Saints, and church leaders (including the First Presidency and Quorum of the Twelve) secretly authorized further plural marriages until the first decade of the twentieth century. Mitt Romney's ancestors were especially prominent in this "Post-Manifesto" era of Mormon polygamy, as many post-Manifesto plural marriages were solemnized in Mexico. Two common misconceptions about Mexican post-Manifesto polygamy are that polygamy was legal in Mexico, and that the Manifesto did not apply outside the United State. In actuality, polygamy was illegal in Mexico, and church leaders had agreed to discontinue polygamy throughout the world, not just in the United States. President Woodruff stated that the prohibition on plural marriages applied to Mormons "everywhere and in every nation and country."
News of post-Manifesto plural marriages inevitably leaked out, and when Reed Smoot was voted into the Senate in 1904, he was not allowed to sit without hearings examining the LDS church's commitment to stopping polygamy entirely. These hearings were a considerable embarrassment to church leaders. Under great pressure, Joseph F. Smith released what is known as the "Second Manifesto" in 1904.
Because of the embarrassing revelations of "new polygamy" in the Reed Smoot hearings (1904-06), LDS church leaders ceased authorizing new plural marriages. President Joseph F. Smith issued a "second manifesto." That's when the LDS church said it would excommunicate members for entering into or solemnizing polygamous marriages. Again, there was no penalty expressed for continuing in a pre-Manifesto polygamous marriage. The Second Manifesto has never been canonized by the LDS Church.
Apostles John W. Taylor and Matthias F. Cowley were vocal in their objection to the Second Manifesto and were removed from the Quorum of the Twelve Apostles in 1906, and Smith was excommunicated for his continued opposition in 1911.
1911.
That's when the LDS Church really began to enforce the Second Manifesto. The 1890 Manifesto was not enforced. It was more of a "nudge, nudge, wink, wink" deal.
This post has nothing to do with LDS theology. It has to do with history. The LDS Church no longer permits polygamy, but to say that the church ended polygamy with the 1890 Manifesto is at best simplistic and at worst a lie.
However, most people who say that polygamy ended with the 1890 Manifesto have been taught faith-promoting history all their lives and have no idea about the difficult history of abandoning something so integral to the LDS Church. Most have probably never heard of Reed Smoot and know nothing of the 1904 Second Manifesto.
Again, the LDS Church no longer permits polygamy despite the fact that Doctrines and Covenants 132 is still on the books.
Yeah. I'm frankly tired of the Media myth -- the media misunderstanding on polygamy -- as force-fed to them by the deceitful PR department of the Mormon Church.
As you mention, Scoutmaster, individual grassroots who've been force-fed "faith-promoting history" have largely been "simplistic" -- to think that all polygamous living arrangements suddenly vanished in 1890 with the wave of a Woodruff hand.
But the Mormon Church can't get off so easy. They know polygamy continued. B. Carmon Hardy in his book, Solemn Covenant, documents 262 additional plural marriage unions that came into "fruition" between 1890-1910. None of these would have been official had the Mormon church not arranged for a proper authority to solemnize the act. I reviewed that list and concluded that the last of these plural unions died out around the early 1960s.
So officially mainstream Mormon polygamy continued through less than 50 years ago. And Hardy's book was published in the early 1990s...so as Scoutmaster says, researchers over the past 20 years have continued to document hundreds -- if not thousands -- of additional plural unions. It may be, as Scoutmaster says, in excess of 2,000 that were performed through 1910.
ALL: Therefore, whenever you see a Mormon official use the "1890" year, know that he is speaking with forked tongue.
Scoutmaster also cited Lds "apostle" Dallin H. Oaks wrote as claiming "The performance of polygamous marriages also continued for a time outside the United States, where the application of the Manifesto was uncertain for a season." If Mormon officials were "uncertain" about applying the Manifesto, it was only so they could be deceitful about it...as Godzilla mentioned.
The fact is that most of those "performances" were U.S. couples going to Mexico for the solemnization and "honeymoon." IOW, they didn't reside in Mexico. Notice Oaks deceitfully doesn't provide more disclosure on these kind of details.