The transformation of the United States: From colonies to states

Let's use that US territorial expansion gif that I love and use so often to understand this. It happened first with the part of the British Cession in the Northwest Territory, which became the Indiana Territory when Ohio became a state. The Mississippi Territory included Alabama, the Louisiana Territory became the Missouri Territory when Louisiana became a state, then splitting into the Arkansas Territory at the same time as Oregon Country was established in the Northwest. As Missouri and Arkansas joined, the interior became the unorganized territory. This trend of a territory taking a name and then losing that name when the first state within it was made official seems to be common. This reorganization and renaming of territories kept happening until the contiguous 48 states were established. And the territorial evolution shows us how so many of the western states, especially, share a common heritage in these territories, having slowly split from them one by one. It would however potentially be a mistake to claim that for instance Montana split from Nebraska just because it originates from the Nebraska territory. In many cases that is just a matter of the name that happened to be chosen as the first one of the territory, although some seem to be real territory splits. For instance, the New Mexico territory was established from the Mexican cession and became unorganized territory in 1850 in what is today Arizona and New Mexico, only splitting into the two in 1862 due to the local desire of the people of Arizona, they were actually the last two of the contiguous 48 to to reach statehood.