when did the us acquire the last of the territory that would make up the 48 contiguous states
Territorial evolution of the United States Regarding internal borders, while territories could shift wildly in size, once established a state has commonly remained within its borders, barring small changes due to river shifts. Only four states – Maine, Kentucky, Vermont, and West Virginia – have been created from land claimed by another state; all of the others were created from territories or directly from acquisitions. The last state of the contiguous United States, commonly called the "lower 48," was admitted in 1912; the fiftieth and most recent state was admitted in 1959.