  The global structure of 2-dimensional dilaton gravity is studied, attending
in particular to black holes and singularities. A gravitational energy is
defined and shown to be positive at spatial singularities and negative at
temporal singularities. Trapped points are defined, and it is shown that
spatial singularities are trapped and temporal singularities are not. Thus a
local form of cosmic censorship holds for positive energy. In an analogue of
gravitational collapse to a black hole, matter falling into an initially flat
space creates a spatial curvature singularity which is cloaked in a spatial or
null apparent horizon with non-decreasing energy and area.
