In article ,
Ron Garret wrote:

The assigned route was not on an airway, and so there is no minimum IFR
altitude on the route.

Correction (because I know the FAR mavens are going to be all over me
for that one): I should have said, "The minimum IFR altitude is not
easily determined." By the book it's either 1000 or 2000 feet about the
highest obstacle within 4 nautical miles depending on whether or not the
area is designated mountainous. Taking that rule and actually figuring
out where you are supposed to begin to climb and how high (and, more to
the point, where you are supposed to begin to descend, because your
destination is just on the other side of the mountains in this case) is
not such an easy thing to do in flight.

rg