Wisconsin Territory became an organized territory of the United States by an act of U.S. Congress passed on April 20, 1836 which went into effect on July 3, 1836. Belmont, Wisconsin was initially chosen as the capital of the territory, but this was changed in October 1836 to the current capital of Madison.
The Territory became the state of Wisconsin, the 30th U.S. state on May 29, 1848.
The Wisconsin Territory included all of present-day states of Wisconsin, Minnesota, Iowa and part of the Dakotas up to the Missouri River. Much of the Territory had originally been part of the Northwest Territory, which was ceded by Britain in 1783. The portion in what is now Iowa and the Dakotas was originally part of the Louisiana Purchase and was split off from the Missouri Territory in 1821 and attached to the Michigan Territory in 1834.
The area encompassed by the Wisconsin Territory that was part of the Northwest Territory was included with the Indiana Territory, when that territory was formed in 1800, in preparation for admission of Ohio as a state. In 1809, it was included with the Illinois Territory, when that was split off from the Indiana Territory. In 1818, when Illinois was about to become a state, the area was joined to the Michigan Territory. Wisconsin Territory was split off from Michigan Territory in 1836 as the state of Michigan prepared for statehood. In 1838, Iowa Territory was formed, reducing Wisconsin Territory. Present state of Wisconsin encompassed most of Wisconsin Territory; the residual portion of Wisconsin Territory was officially dissolved and incorporated into Minnesota Territory in 1849.
President Andrew Jackson appointed Henry Dodge Governor and John S. Horner Secretary. The first legislative assembly of the new territory was convened by Governor Henry Dodge at Belmont, Wisconsin in the present Lafayette County on October 25, 1836.
However, there are irregularities in the timeline at the outset of the Territory. After Congress refused Michigan's petition for statehood, despite meeting the requirements specified in the Northwest Ordinance, the people of Michigan authorized its constitution in October, 1835 and began self-governance at that time. Yet, Michigan did not enter the Union until January 26, 1837, and Congress did not organize the Wisconsin Territory separately from Michigan until July 3, 1836.
Hoping to provide for some continuity in governance during that interim, the acting Governor of the Michigan Territory, Stevens T. Mason, issued a proclamation on August 25, 1835 that called for the election of a western legislative council, which became known as the Rump Council. This council was to meet in Green Bay, Wisconsin on January 1, 1836. However, because of the controversy between Michigan and Ohio over the Toledo Strip, known as the Toledo War, President Jackson had removed Mason from office on August 15, 1835 and replaced him with John S. Horner. Horner issued his own proclamation on November 9, 1835, calling for the council to meet on December 1, 1835 — giving delegates less than a month to learn of the change and travel to the meeting. This caused considerable annoyance among the delegates, who ignored it. Even Horner himself neglected to attend. The Council convened on January 1 as previously scheduled, but Horner, while reportedly intending to attend, was delayed by illness and in the Governor's absence the council could do little more than administrative and ceremonial duties. For its concession to the Toledo Strip, Michigan was given the Upper Peninsula.
I understand State Senator Fred Risser was quoted at the time saying, "At least I won't have to go all the way to Belmont."