at no time in the Civil War did the Union Army have a 4 to 1 manpower advantage over the Confederate Army.
You are trying to parse the facts to create the illusion you want. From before the war, the Union had a 4 to 1 advantage in manpower. This extends to logistical support, just as the people who remained here operating the factories during WW2 were also part of the war effort.
By trying to make it only about the Union army, you are being disingenuous.