Which state was not included in the territories governed by the Treaty of Guadalupe Hidalgo?

The Treaty of Guadalupe Hidalgo, signed in 1848, ended the Mexican-American War and resulted in significant territorial changes in the United States. The treaty provided the U.S. with vast lands that included present-day California, New Mexico, Arizona, Nevada, Utah, and parts of Colorado and Wyoming, as well as recognizing Texas as part of the U.S. Therefore, both California and New Mexico were indeed part of the territories acquired under this treaty. Texas had also been annexed by the U.S. prior to the treaty and was not a newly acquired territory under it.

Arkansas, on the other hand, was already a state in the Union prior to the signing of the Treaty of Guadalupe Hidalgo and was not included in the territorial changes that resulted from the treaty. Thus, it’s clear that Arkansas was not part of the territories governed by the Treaty of Guadalupe Hidalgo, making it the correct answer. This distinction highlights Arkansas's status as a pre-existing state versus the newly acquired territories resulting from the treaty.