Final answer:
The Cross Timbers itself did not politically divide a state, but the issues of territorial expansion and slavery within newly acquired territories like Texas were central to 19th-century political divisions in the U.S., ultimately contributing to the Civil War.
Step-by-step explanation:
The cross-timbers, likely a reference to a geographical area, did not directly divide a state politically; rather, territorial expansion and the contentious issue of slavery were at the heart of political division in the United States during the 19th century. The annexation of Texas and the resulting acquisition of new lands after the US-Mexican War brought the issue of slavery expansion to the fore. Concerns regarding the balance of power between slave and free states, property rights, and the economic implications of slavery influenced political parties and policy decisions. North and South divisions led to the formation of anti-slavery parties and increasingly aggressive political stances.
Both the Democratic and Whig parties grappled with the complexities of territorial expansion and slavery. The Democrats generally supported expanding the nation's territory, including annexation of lands from Mexico, while Whigs cautioned against this, especially when it risked exacerbating tensions over slavery's extension into new territories. The Missouri Compromise, the Compromise of 1850, and other attempted legislative solutions could not ultimately reconcile the differences between the two regions. The political rift grew, leading to the eventual secession of Southern states and the onset of the Civil War.