path elevation profiles?

[Glenn Elmore <glenne@hpnmdlc1.hp.com>]

  Does anyone know of an accessible database which can provide elevation
profile information over an arbitrary path within the continental US?
  As we start to improve the physical and link layers we are going to
have to pay closer attention to Line-Of-Sightedness of our radio paths.
I know that USGS has this sort of information and I believe 3D topo maps
exist in some locations (Redwood City, CA?)  but I'm looking for a more
general way to analyze potential paths.
  Right now I'm trying to get high level sites lined up and it sure
would be nice to be able to tell if potential sites are LOS or not and
by how much margin.
  Maybe I'll just have to "bite the bullet" and study existing hardcopy
maps but I was hoping for a better and easier way....

  Anyone have ideas?

Glenn Elmore -N6GN-

N6GN @ K3MC
glenn@n6gn.ampr.org
glenne@hpnmd.hp.com