Answer: The annexation of Texas in 1845.
Step-by-step explanation:
Texas thus became 28 states of the United States. Texas, as early as 1836, demanded that the United States annexe it for not accepting political exits. Efforts were made to avoid a conflict with Mexico as Texas seceded without the will of the Mexicans. In 1843, US President John Tyler sought to annex Texas to secure additional votes from the area in the next election. However, after some political upheaval, this attempt failed. Yet Texas becomes part of the United States two years later. The bill was signed by President Polk on December 29, 1845, accepting Texas as the 28th state of the Union. The move will make a dispute between the US and Mexico because the border issue has not been resolved, culminating in a war between the two countries.