|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|
- February 4 - First Saints start migration from Nauvoo to the West.
- February 4 - The ship Brooklyn sails from New York for California under the direction of Samuel Brannan.
- April 24 - Temporary migratory settlement established at Garden Grove, Iowa.
- July 13 - Mormon Battalion formed.
- July 31 - The ship Brooklyn arrives in Yerba Buena, California (later named San Francisco).
- September 17 - Battle of Nauvoo drives last Saints from the city.