Why was the main reason the Union set up blockade?

The main reason the Union set up a blockade during the Civil War was to cut off the Confederacy's access to essential supplies, resources, and trade routes. By blockading Southern ports, the Union aimed to weaken the Confederate economy, limit its ability to import goods and export cotton, and ultimately diminish its capacity to sustain the war effort. This strategy was part of the Anaconda Plan, which sought to suffocate the South's resources and morale over time.