Contrary to popular belief, Texas is not the only state that has once been its own independent nation. Hawaii, California, South Carolina, Vermont, and the no longer existant West Florida all have histories of being their own nations. North Carolina and Rhode Islands were also briefly their own nations as well.
Texas does not have the right to secede from the Union, but it does however, have the right to split itself into as many as five states on the approval of its legislature for the purpose of increased Senate representation.
Texas is the second largest state in the US in terms of both area and population, with Alaska being larger and California more populous.
Texas became the 28th state in the United States in 1845.