Which state is unique in that it entered the United States via treaty?

Texas is unique in that it entered the United States through a treaty. After gaining independence from Mexico in 1836, Texas became its own republic, known as the Republic of Texas. When Texas sought to join the United States, a treaty was negotiated. In 1845, Congress passed a resolution to annex Texas, which was then ratified by the republic's government. This process is distinct because typically, states have entered the Union through legislative actions rather than treaties.

This annexation by treaty emphasizes Texas's historical context and its prior existence as a sovereign nation, which is not the case for the other states listed. California, Oregon, and Alaska were acquired through different means, such as military conquests or territorial purchases, rather than through a formal treaty after being an independent entity. Thus, the unique process associated with Texas's admission highlights its historical importance and the distinct relationship between Texas and the United States.