|Centuries:||18th century - 19th century - 20th century|
|Decades:||1810s 1820s 1830s - 1840s - 1850s 1860s 1870s|
|Years:||1840 1841 1842 1843 1844 1845 1846 1847 1848 1849|
- Brigham Young is appointed as President of the Quorum of the Twelve Apostles
- January 19 - D&C 124 recorded by Joseph Smith in Nauvoo, Illinois.
- January 30 - At a special conference held in Nauvoo, Illinois, Joseph Smith was unanimously elected sole Trustee-in-Trust for the Church.
- February 1 - First municipal elections held in Nauvoo, Illinois, with John C. Bennett elected mayor.
- February 3 - Nauvoo Legion created by order of the Nauvoo city council.
- February 3 - University of the City of Nauvoo created by order of the Nauvoo city council.
- October 24 - Orson Hyde dedicates Palestine for the gathering of the Jews.
- Nauvoo Masonic lodge founded (York Rite Freemasons)