This is a timeline of major events in Mormonism in the 20th century. __NOTOC__
1900s
1900 January 25: The U.S. Congress votes to not admit B. H. Roberts, who had been denied a seat since being elected in 1898, because of his practice of polygamy. April 19: Reed Smoot is ordained an apostle.
1901
April 10: The Daughters of Utah Pioneers organization is founded. September 1: Japan is dedicated by Heber J. Grant for missionary proselyting. October 10: Lorenzo Snow dies. October 17: Joseph F. Smith becomes the sixth president of the LDS Church.
1902 January: The first issue of The Children's Friend is published, a magazine for LDS primary children. August 4: The Bureau of Information opens on Temple Square, the first visitors' center of the LDS Church. September 20: The first volume of the History of the Church is published, edited by B. H. Roberts and covering Joseph Smith's life from 1805 to 1833.For the publication date, see advertisements placed in the Deseret Evening News: October: A new edition of the Pearl of Great Price is approved, as prepared by James E. Talmage, who introduced chapters and verses and removed material duplicated in the Doctrine and Covenants.
1903
January: Reed Smoot, an apostle, is elected by the state legislature to the 58th congress as a U.S. Senator. Controversy over his election arises immediately. February: Despite allegations and controversy, Reed Smoot is allowed to be seated in the Senate. March: Reed Smoot takes the senatorial oath and formally becomes a member of the senate. October 15: Brigham Young Academy becomes Brigham Young University. November 5: The LDS Church acquires Carthage Jail, to be used as a historic site. Samoan edition of the Book of Mormon.
1904
January – Reed Smoot submits carefully prepared rebuttals to allegations against him and his church. March – The Reed Smoot Hearings begin, evaluating whether Reed Smoot should be allowed to be a senator. April 6 – Joseph F. Smith issues the "Second Manifesto", which reinforces the 1890 Manifesto and prescribes excommunication for those who continued to practice plural marriage. April 14 - The LDS Church purchases 25 acres in Independence, Missouri, originally part of the 63-acre Temple Lot from 1831. Church leaders intended this to be the site for a temple in Zion, fulfilling a prophecy of Joseph Smith.
1905 January 1: Latter-day Saint Hospital is opened. April: John W. Taylor resigns from the Quorum of the Twelve Apostles due to disagreements with church policy regarding polygamy. October 28: Matthias F. Cowley follows John W. Taylor and resigns from the Quorum of the Twelve Apostles due to disagreements with church policy regarding polygamy. December 23: Joseph Smith Birthplace Memorial near Sharon, Vermont is dedicated by Joseph F. Smith.
1906 Summer: Joseph F. Smith visits Europe, the first President of the Church to do so. The first Sunday School classes for adults are held. Turkish edition of Book of Mormon; first in an Asian language.
1907
January 10: The LDS Church becomes debt-free. February 20: After more than two years of hearings, the Smoot Hearings are resolved by a vote. The republican majority overturns objections to his seating. Reed Smoot serves another 26 years. June: The Smith Family Farm is acquired for the LDS Church. December 7: Charles W. Nibley becomes the Presiding Bishop and brings financial reforms, including tithing payments only in cash, no longer taking donations in kind. December 14: Converts in Europe are advised to remain in their home countries instead of gathering to Utah. Zion's Printing and Publishing Company is started at Independence, Missouri by the LDS Church.
1908 April 8: The General Priesthood Committee is created. October: A financial auditing report is presented at General Conference for the first time.
1909 November: The First Presidency issues an official statement regarding questions concerning the Creation of the earth and the theories of evolution and the origin of man. LDS Church purchased property in Far West, Missouri, including the former temple lot. LDS priesthood meetings begin to be held weekly. Japanese translation of Book of Mormon, the first in an east Asian language.
1910s
1910 January: The Utah Genealogical and Historical Magazine is launched, published by the Genealogical Society of Utah. April 14: Daughters of the Utah Handcart Pioneers founded.
1911
February 10: Three popular BYU professors appear before church leaders for teaching evolution. After becoming a public controversy, the professors resign later that year. Historian Leonard Arrington called this Mormonism's "first brush with modernism". March 28: John W. Taylor is excommunicated for performing a plural marriage despite the Second Manifesto issued by church president Joseph F. Smith. With this excommunication, the practice of new polygamous marriages is believed to be finally abolished. Polygamists who were married prior to 1905 continue to remain in good standing with the LDS Church including, but not limited to, the church's president, Joseph F. Smith. April 15: Theodore Roosevelt publishes an article in Collier's magazine defending the Mormons, in response to an ongoing anti-Mormon campaign in national magazines. April–May: Mexican Revolution. The Battle of Ciudad Juárez brings war to the doorstep of the Mormon Colonies in Mexico in the Casas Grandes valley. June 9: The Hotel Utah opens across from Temple Square in Salt Lake City. August: James E. Talmage denounces the Michigan relics as fakes. September 16: A photographer threatens to publicly display unauthorized photographs of the interior of the Salt Lake Temple unless the church pays $100,000. Instead president Joseph F. Smith arranges the church to publish a book containing its own such photos. October: A Victim of the Mormons (Danish: Mormonens Offer) a Danish silent film directed by August Blom is released. The film was controversial for demonizing the Mormon religion, and its box-office success is cited for initiating a decade of anti-Mormon propaganda films in America. October 26: Stake missionaries are first called, in the Granite Utah Stake. November 29: The M.I.A. Scouts are created as the first official LDS organization of the Boy Scouts of America.
1912 Summer: Mormon colonies in Mexico are evacuated due to anti-American sentiment during the Mexican Revolution, and many of their citizens leave for the United States and never return. Some colonists did eventually return, but today only Colonia Juárez and Colonia Dublan in the Casas Grandes river valley remain active. September 30: James E. Talmage's The House of the Lord published. It is the first book to have official photographs of temple interiors. September: The first LDS seminary opens with religious classes for students from Granite High School in Salt Lake City, Utah. November 8: The Correlation Committee is organized to help eliminate redundancy in LDS Church auxiliaries. Publication of Riders of the Purple Sage, by Zane Grey. It is his best known novel and played a significant role in shaping the formula of the popular Western genre. However it contains unflattering portrayals and stereotyping of Mormon polygamists.
1913
May 21: The Boy Scouts of America program is officially adopted for use in the LDS Church. October 1: Joseph F. Smith dedicates the Seagull Monument in the Temple Square of Salt Lake City, Utah. One Hundred Years of Mormonism premiers. Maori Agricultural College is created in New Zealand by the LDS Church.
1915 January: Relief Society Magazine begins publication for LDS women. April 27: Home Evening program is introduced, calling for families to study the gospel together at home. September: Jesus the Christ by James E. Talmage is published. It remains popular to this day.
1916 June 30: "The Father and the Son", an official declaration from the First Presidency, discusses the identities of Heavenly Father and Jesus Christ.
1917 October 2: The Church Administration Building is completed. Russian Revolution which results in the Soviet Union after a protracted civil war. The region is not opened to missionaries until the early 1990s and travel to there by outsiders becomes more difficult.
1918
May 16: Arrangements are announced for the Relief Society to sell its wheat storage of over 200,000 bushels to the U.S. government, to cover military food shortages near the end of World War I. October 4: Joseph F. Smith announces at General Conference his revelation about the ministry to those in the afterlife, now known as Section 138 of the Doctrine and Covenants. October 31: The Quorum of the Twelve and the Patriarch of the Church unanimously accept Smith's revelation as official church canon. November 19: Joseph F. Smith passes away. November 23: Heber J. Grant becomes the seventh president of the LDS Church.
1919 April: General Conference is postponed to June because of the Spanish flu epidemic. November 27: Laie Hawaii Temple first outside continental United States, and thus also arguably first outside North America and first in Polynesia. LDS Church membership reaches 500,000.
1920s
1920 December 2: Apostle David O. McKay and Hugh J. Cannon, editor of the Improvement Era, are set apart for a year-long tour of LDS missions and schools across the world. As the most widely traveled general authority, McKay retains a vision for worldwide church growth. The LDS Church closes its system of academies.
1921 Lectures on Faith removed from Standard Works. New programs for young adults are created, called M-Men and Gleaners. Joseph Fielding Smith's Essentials in Church History is published, an influential book of devotional LDS history that remained in print for more than 50 years.
1922 February 7: Zions Securities founded. May 6: KZN radio (later KSL) goes on air in Salt Lake City, with LDS Church involvement, and makes a message of Heber J. Grant the first church broadcast. May: Primary Children's Hospital opens in its first facilities. Trapped by the Mormons (also released as The Mormon Peril), a 1922 silent British anti-Mormon film directed by H. B. Parkinson, is released.
1923 August 26: Cardston Alberta Temple, first outside United States, and first in another country. LDS Church first acquires part of the Hill Cumorah, the site where Joseph Smith reported finding the Golden Plates.
1924 January: Lorin C. Woolley is excommunicated from the LDS Church for alleging that church president Heber J. Grant and apostle James E. Talmage had taken plural wives in the "recent past". He claimed to have learned this while spying on LDS Church leaders for the United States Secret Service. Grant publicly denied these claims in general conference in April 1931.Brian C. Hales, "'I Love to Hear Him Talk and Rehearse': The Life and Teachings of Lorin C. Woolley" , Mormon History Association, 2003. Wooly later founded the polygamous Mormon fundamentalism movement. April: A microphone is first used in General Conference, allowing overflow attendees to hear the proceedings in another building on Temple Square. October 3: The first General Conference radio broadcast.
1925 July 18: In the wake of the Scopes Trial, the First Presidency issues an official statement, an edited version of the 1909 statement, regarding questions about the Creation of the earth, the theory of evolution, and the origin of man. February 3: The Salt Lake Mission Home is dedicated, for use in training of LDS missionaries before they depart for their assignments. April 21: The LDS Church buys a controlling interest in a Salt Lake City radio station, which it changes from KZN to KSL and still maintains today. December 25: South America is dedicated for missionary proselyting, by LDS Apostle Melvin J. Ballard in Buenos Aires, Argentina.
1926 Fall: The first Institute of Religion is founded in Moscow, Idaho, adjacent to the University of Idaho.