What advantages did the North have over the South in the U.S. Civil War?

I would place
the US Navy as the number one
advantage, with the manufacturing capability as second and the
population
advantage as third.

The existence of a Navy meant the Union
could
blockade the ports of the Confederacy.  it took a while to effect this
blockade to the point it
was a stranglehold but it was key to the defeat of
the Confederacy, just as Winfield Scott
predicted it would be in his Anaconda
plan.

The industrial capacity of the
North and the
advantage in railroad mileage allowed the North to take advantage of its

industrial advantage.

Population was critical, the Confederacy had 9
million
citizens, but 3,500,000 of these were slaves, and 110,000 involved in
industrial production.  
Union had 22 million people with 1.3 million
involved in industrial production.

The U.S. had some
military technological advantages, although gatling guns were not
used
sufficiently to make a difference, breach loading repeating rifles made a difference in
a
number of battles such as Gettysburg, and the US had an advantage in rifled
muskets over smooth
bores.  There were more telegraph capabilities in the
Union than Confederacy.  The confederacy
did launch manage to use submarines,
but they had limited effect, and while the Confederacy had
the first
ironclad, it was quickly overwhelmed on that score by the Union, and the recapture
of
the Norfolk naval yards by the Union pretty much ended the Confederacy's
efforts in that
area.

Finally the Union had a stronger
conception of a nation, the
Confederacy less so, which meant it was forced to
try and defend all of its sprawling territory
rather than trying to
prioritize, stretching its already thin manpower resources even

thinner.

The confederacy prided itself on having better battle elan,
and
espirit de corps, but if you actually look at the battle spirit of Union
forces, you will see
that they rivalled that of their southern
adversaries.