Thank you for your reply! I really appreciate it.
I tried editing the footprints to exclude the area that was black, but it did not affect the appearance; the black is still there.
However, the black areas are only black when I am zoomed out past 1:4000. At 1:4000 or larger (closer), they disappear and I can see the map as it should be, without the black areas. (The black areas are chunks of certain map sheets that I made transparent before putting them into ArcMap.)
Also, I've discovered that the black areas are "No Data" - I changed the NoData coloring to No Color, and now those areas are white instead of black. And they still go away when I zoom in.
So, does anyone know how to get the map to display properly at all scales? Thank you for your time!
Allen