The southern states were largely in favor of annexing Texas for several reasons, primarily related to economic interests, political power, and the issue of slavery.
First and foremost, Texas was a vast territory with fertile land that promised great agricultural opportunities, especially for cotton and sugar plantation owners. The South was already heavily invested in agriculture, and the prospect of adding the rich lands of Texas was very appealing to southern farmers who sought to expand their resources and profits.
Politically, the annexation of Texas was seen as a way to increase the power of slaveholding states in the U.S. Congress. At the time, the balance of power between free and slave states was a contentious issue. By bringing in Texas, which allowed slavery, the South aimed to bolster its political influence and protect its interests against the growing abolitionist movement in the North.
Furthermore, there was a strong belief in the idea of Manifest Destiny, the notion that the United States was destined to expand across the continent. Many southerners saw the annexation of Texas not only as a means to achieve economic and political goals but also as a fulfillment of this national vision of expansion.
In summary, the southern states supported the annexation of Texas due to its potential for agricultural wealth, the desire to maintain political power in a shifting national landscape regarding slavery, and a broader ideology of territorial expansion.