how to snap (align) edge to (with) a vertex in another object I'm new to blender and am having a difficult time with very simple tasks, such as moving an edge in one object to align with (snap to) a vertex in another object.

I want to grab the right vertical internal edge inside the upper rectangle and move (translate it) to the right so that it aligns with the upper-right vertex in the rectangle below . . . 

I've tried "Snap during transform", "Snap to vertices", and tried "Closest", "Active", "Median" and "Center". I pressed G to grab the edge, but it won't snap to the vertex on the lower square.  I also tried regular "Snap", but it collapses the entire edge to a single point. 

I think I've tried everything, but nothing has worked. Many thanks for any advice!
I think it might be that you're not moving the edge under a constraint, so you can't hover over the target without dragging the whole edge down to it. 

The 'Active', 'Closest' etc. settings refer to the source of the snap, the moving element. The 'Vertex', 'Face', etc. button next door refers to the target, the still element.

The most intuitive setting, I think, is (source)'Active', (target)'Vertex', used with a selection of source vertices made, one of them active, aiming to align with a target vertex. 

So try it that way, with all the vertices of your edge(loop?) selected, using GX, constraining the move, leaving your mouse free to hover over the target vertex, without pulling the selection with it.