Why did the siege of Vicksburg affect the balance of power during the Civil War?

The Siege of Vicksburg allows for a huge shift in power during the Civil War. This is due to the fact that the Union gains control of the Mississippi River. The Mississippi River was a critical stronghold of the Confederacy, as this was the source they used to transport goods and soldiers. Now that the Union controlled this, it essentially cut the Confederacy in half. This would greatly weaken the Confederate war effort and lead to their ultimate loss to the Union.