Texas formally relinquished its sovereignty to the United States on February 19 , 1846 .
The bill was signed by Polk on December 29 , 1845 , accepting Texas as the 28th state of the Union .
Texas formally relinquished Texas ' sovereignty to the United States on February 19 , 1846 .
The bill was signed by Polk on December 29 , 1845 , accepting Texas as the 28th state of the Union .