Why did the union wanted to control the west?

The Union wanted to control the West during the Civil War primarily to secure valuable resources, expand agricultural and economic opportunities, and promote settlement in these territories. Controlling the West would also help prevent the spread of slavery, as many Union leaders believed that the expansion of free states would weaken the Confederacy. Furthermore, establishing a strong presence in the West was seen as essential for maintaining national unity and bolstering the Union's strategic advantages.