RE: Population Density Maps
I would deal with all aspects of the left side (1790) first, followed by the same process for the right side (1830). You haven't said what grade level this is for, but first of all I would show the states and names of the states. You will need to explain in a transcriber's note, that it is split into 2 parts (1790 & 1830). You will also need to explain how you are going to divide this into layers to show the information.
Depending on the surrounding information and grade level, you may be able to list the names of the states and territories, and then label the uncommon ones on a simple map with only the borders shown—but no mention of the population. The second part of the 1790 side should show textures for the various levels built up upon each other. Use a distinct texture such as medium sandpaper for the highest numbers (red area) on the legend, since those are the smallest areas on the map. I would probably also combine some of the numbers in the legend. For example, the lowest texture would represent 2 or less, the next would represent 2-18, followed by one for 18-45, and then 45-90 or more. On this second map page, you would show only the population density layers and omit the borders and labels of the states. Be sure that each time the tactile key is on a facing page to the map itself.
Again, depending on the surrounding text and purpose of the tactile, you may not need to reproduce the scale and compass rose. Without seeing that information, I assume that the main purpose it stated in the title—the population density. This type of tactile is best suited to the collage method of production. By showing the state & territory names first, the reader is provided with an overview of how the area changed as the population spread. I would keep both maps the same size as each other.
Then repeat with the 1830 map.
Hopefully this makes sense!