The relief map of Washington is based on the Color Landform Atlas of
the United States at the Applied Physics Laboratory of Johns Hopkins
The colored map proved too memory-costly for my purposes, so I used Graphic Converter to change it from 32-bit to 4-bit, thus preserving some of the relief patterns in grey-scale (reminds me of an old Republic or RKO studio black-and-white movie, actually).
Years ago I digitized the county boundaries showing county evolution (a continuation of my dissertation work on the evolution of county size). Some time after that I wrote a BASIC program to display the evolution process and, still later a Mac Hypercard script to do the same thing. All I had to do here was invert the boundaries (black to white) in Graphic Converter, then paste them over the relief map (in Canvas), then copy and paste the result to GIFbuilder to achieve the animation.