Why did southerners agree to give up the transcontinental railroad and support the kansas -nebraska act act?

Southerners agreed to give up the transcontinental railroad in favor of supporting the Kansas-Nebraska Act because they sought to expand slave territory and ensure the political power of slaveholding states. The Act allowed for popular sovereignty, enabling settlers in Kansas and Nebraska to decide whether to permit slavery, which aligned with Southern interests. Additionally, by prioritizing the railroad's southern route, they aimed to secure economic benefits and strengthen their position in Congress. This compromise was seen as a way to maintain the balance of power between free and slave states.