  We enumerate the edges in the Hasse diagram of several lattices arising in
the combinatorial context of lattice paths. Specifically, we will consider the
case of Dyck, Grand Dyck, Motzkin, Grand Motzkin, Schr\"oder and Grand
Schr\"oder lattices. Finally, we give a general formula for the number of edges
in an arbitrary Young lattice (which can be interpreted in a natural way as a
lattice of paths).
