In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

The Territory of Arizona ( also known as Arizona Territory ) was a territory of the United States that existed from February 24 , 1863 until February 14 , 1912 , when the remaining extent of the territory was admitted to the Union as the state of Arizona .
The Arizona Territory was an American territory from February 24 , 1863 to February 14 , 1912 .