The Territory of Utah was an organized incorporated territory of the United States that existed from September 9, 1850, until January 4, 1896, when the final extent of the territory was admitted to the Union as the State of Utah, the 45th state. At its creation, the Territory of Utah included all of the present-day State of Utah, most of the current state of Nevada save for that portion of Southern Nevada (including the metro area of the city of Las Vegas), much of modern western Colorado, and the extreme southwest corner of present-day Wyoming.

When the Mormon pioneers moving westward across the Great Plains began settling the Salt Lake Valley around the Great Salt Lake in 1847 and for many years afterward, they relied on existing institutions within the Church of Jesus Christ of Latter-day Saints (Mormon or LDS Church) or the secular civil governments.

The Utah Territory was organized by an Organic Act of the United States Congress, approved by the newly succeeded 13th President Millard Fillmore (1800–1874, served 1850–1853), only two months after the former Vice President acceded to the higher office upon the sudden death in July 1850 of his military general predecessor Zachary Taylor. The Utah Territory bill was approved by him in September 1850, on the same day that the State of California was admitted to the Union as the 31st state (and the first time the American Union jumping across the North American continent to the opposite Pacific Ocean west coast). Plus the original larger New Mexico Territory in the Great Southwest was added and erected from the southern portion of the huge Mexican Cession in 1849 of former Centralist Republic of Mexico lands, (which amounted to the northwestern one-third of their country) following their defeat in the Mexican–American War.of 1846-1848. The creation of the new Territory of Utah around the Great Basin and the Great Salt Lake was part of the elements of agreements in the political Compromise of 1850 made in the national capital of Washington, D.C. that sought to preserve the balance of power between Southern slave states and free states in the North. With the exception of a small area around the headwaters of the upper Colorado River in present-day Colorado, the United States had acquired all the northwestern lands of the territory and former provinces from southern neighbor Mexico after the negotiations and ratification of the Treaty of Guadalupe Hidalgo of 1848, following several additional battles along the Gulf of Mexico coast and central heartland, resulting in the occupation of the Mexican capital of Mexico City by Invading American military forces and their surrender with the end of the brief war. The peace treaty later passing in Congress in the upper chamber of the U.S. Senate, (which approves all foreign treaties according to the U.S. Constitution) and the lower chamber of the House of Representatives voted in the subsequent supplemental legislation in favor of organizing the federal Territory of Utah, 97–85.

The creation of the Territory with no mention at all of the divisive issue of slavery in the documents, was partially the result of a petition sent by the Mormon pioneers under the leadership of Brigham Young (1801–1877, served 1847–1877), the second church president. The petition had asked Congress to allow them to enter the Union as the State of Deseret, (which they had already organized the year before) with its capital as Salt Lake City and with proposed borders that encompassed the entire Great Basin and the watershed of the Colorado River, including all or part of nine current U.S. states in the southwest. The Mormon settlers had drafted a state constitution in 1849 and Deseret had become the de facto government in the Great Basin by the time of the creation of the subsequent Federal Utah Territory.

Following the organization of the Territory, second church president Young was inaugurated as its first territorial Governor of Utah. The first Territorial Capital City and Capitol building was located 1850 to 1856 in the small town of Fillmore, Utah, named for the new 13th President Millard Fillmore, who approved and signed the Congressional organic act and territorial erection bill of September 1850, and the small local government was set up here including the meetings of the Territorial Assembly, although first Governor and second Church of Jesus Christ of Latter-Day Saints (nicknamed the Mormon church) president Brigham Young remained mostly in his Beehive House (current historic site) residence in Salt Lake City, but traveling to Fillmore 1850 to 1856, until his death in 1877. The capital of Utah Territory was relocated that year of 1856 to the major and largest town of Salt Lake City, which built a new territorial capitol building for the government and its assembly and governor's offices for the next four decades and which also continued as the new state capital after statehood in 1896. A massive monumental Utah State Capitol building with landmark dome was later constructed there on the scenic ridge overlooking from the slopes of the surrounding Wasatch Range mountains to the present.

During Brigham Young's governorship, he exerted considerable power over the territory. An example being that in 1873, the territory legislature gave to Governor / President Young the exclusive right to manufacture and distil whiskey.

Mormon governance in the territory was regarded as controversial by much of the rest of the nation, partly fed by continuing lurid newspaper depictions of the polygamy marriage practiced by the settlers, which itself had been part of the cause of their flight from their previous homes and center back East in Nauvoo, Illinois, in the United States, trekking westward across the continent to the Great Salt Lake basin after being persecuted and forcibly removed from their settlements in several Eastern states.

Although the Mormons were now the majority in the Great Salt Lake basin, the western area of the new territory soon began to attract many non-Mormon settlers, especially after the discovery of silver at the famous Comstock Lode ore deposits in the Virginia City area, east of the Sierra Nevada mountain ranges and Lake Tahoe (of present-day western Nevada) in 1858. Only three years later on the eve of the outbreak of the American Civil War in 1861, and partly as a result of this, with its importance of the recovered silver bullion for Federal Treasury coffers plus huge growth in population with the influx of prospecting miners (and assorted supporting commercial business interests) and with the subsequent intensive deep shaft industrial mining and drilling, the new Nevada Territory was then created out of the western part of the previous Utah Territory of a decade before. Non-Mormons also entered the opposite side in the easternmost part of the territory during the Pikes Peak Gold Rush, resulting in the discovery of gold at Breckenridge in Utah Territory in 1859 (ten years after the first mineral findings along the American River in California, resulting in the phenomenal California gold rush of 1849-1855 there). So also in that same year of 1861, additional legislative action was taken by the Congress and the new 16th President Abraham Lincoln (1809–1865, served 1861–1865), to take a large portion of the eastern area of the Utah Territory to be separated and added to as part of the newly created adjacent Colorado Territory further east.

In 1869, the territory's legislature (the Territorial Assembly) approved and ratified women's suffrage. This allowed women to vote in all future territorial elections continuing to 1896 with statehood (although both male and female residents in American territories had no voice or vote in Federal elections back East).

A total of 46 years elapsed between the organization of the territory and its admission to the Union in 1896 as the 45th State of Utah, long after the admission of other federal territories created after it. In contrast, the Nevada Territory to the west, although more sparsely populated, was admitted to the Union in 1864 in the midst of the ongoing American Civil War only three years after its territorial formation, and Colorado was admitted in 1876 during the American Centennial celebration year, fifteen years after first becoming a territory.

The Utah state coat of arms appears on the state seal and state flag. The beehive was chosen as the emblem for the provisional State of Deseret in 1848 and represents the state's industrious and hard-working inhabitants, and the virtues of thrift and perseverance. The sego lilies on either side symbolize peace.

The first flag to represent the Territory flew in 1851 and consist of 13 red and white stripes, a blue canton with 13 stars and eagle that was positioned above a large 5 pointed star. The flag is preserved in Smithsonian institute. The second flag was raised in 1854 and it similarly contained "...stars, stripes, eagle, and beehive." flag was It was raised up flag pole on temple block to celebrated Pioneer's day. The following year at the Governor's mansion on July 4th they "...unfurled the territorial flag." The third flag was depicted on a cigarette trading card in the 1880s. The flag was in a squared ratio with blue background and the Utah state coat of arms in the center. There is no evidence that the flag was ever made or flown.

• 
  Reconstruction of the Territory flag that flew on temple block in 1854
• 
  Territory flag depicted on Allen & Ginter Cigarette trading cards in 1888

Historical population

Year	Pop.	±%
1850	11,380	—
1860	40,273	+253.9%
1870	86,336	+114.4%
1880	146,608	+69.8%
1890	210,779	+43.8%
Source: 1850–1890

In 1850, nine churches with regular services in the Utah Territory were unclassified by historian Edwin Gaustad in his Historical Atlas of Religion in America (1962), but were probably LDS churches. In the 1890 United States census, 25 counties in the Utah Territory reported the following population counts (after seven reported the following counts in the 1850 United States census):

1890 Rank	County	1850 Population	1890 Population
1	Salt Lake	6,157	58,457
2	Utah	2,026	23,768
3	Weber	1,186	22,723
4	Cache	–	15,509
5	Sanpete	365	13,146
6	Summit	–	7,733
7	Box Elder	–	7,642
8	Davis	1,134	6,751
9	Sevier	–	6,199
10	Juab	–	5,582
11	Emery	–	5,076
12	Millard	–	4,033
13	Washington	–	4,009
14	Tooele	152	3,700
15	Wasatch	–	3,595
16	Beaver	–	3,340
17	Piute	–	2,842
18	Uintah	–	2,762
19	Iron	360	2,683
20	Garfield	–	2,457
21	Morgan	–	1,780
22	Kane	–	1,685
23	Rich	–	1,527
24	Grand	–	541
25	San Juan	–	365
	Indian reservations	4,645	–
	Utah Territory	11,380	210,779

• Historic regions of the United States
• History of Utah
• Territorial evolution of the United States

• (1994) "Coins and Currency" article in the Utah History Encyclopedia. The article was written by Leonard J. Arrington and the Encyclopedia was published by the University of Utah Press. ISBN 9780874804256. Archived from the original on March 21, 2024, and retrieved on April 12, 2024.
• (2017) Unpopular Sovereignty: Mormons and the Federal Management of Early Utah Territory by Brent M. Rogers, University of Nebraska Press.

• Utah in 1851, with the text of the 1850 Act of Congress to Establish the Territory of Utah, Central Pacific Railroad Photographic History Museum
• Utah's Role in the Transcontinental Railroad, Central Pacific Railroad Photographic History Museum
• Utah State History Archived April 20, 2021, at the Wayback Machine Utah Office of Tourism Official Website
• Henry Sommer, Watercolors and Pencil Drawings Related to the Utah Expedition. Yale Collection of Western Americana, Beinecke Rare Book and Manuscript Library.

39°50′N 113°30′W / 39.833°N 113.500°W / 39.833; -113.500