I was wondering this when reading The American Civil War by John Keegan. In it he mentions that the Union had almost all of the naval power because of the location of where the ships were docked at the onset of hostilities. Was this planned, or just happy coincidence? Did the Union build forts or strategic outposts in the event of civil war?
Not really planned. It just happened that the major naval yards were in the North because the North had a more pronounced sea-faring community, and generally a more industrial economy better suited for maintaining steamships.
The U.S. Army pre-Civil War was a tiny affair barely suited for keeping the peace on the frontier. There was no General Staff for war planning as was just coming into place with the Prussians. So ill prepared was the Army for the Civil War that an appreciable amount of its arms were seized by the Confederates at the start. The main early fights such as Fort Sumter were over forts that had been built to protect seaports from foreign attack.