Final answer:
A special purpose map would best represent population density in the US, as it can accurately show the distribution of people per area, which is especially important considering the high concentration of populations in urban regions.
Step-by-step explanation:
The map that would best represent population density in the US is a special purpose map. This type of map is specifically designed to show particular themes or subjects, such as population density, which is the number of people living per unit of an area. Unlike a typographical map that primarily shows landforms, a political map that depicts political boundaries, or a climate map that displays climate zones, a special purpose map can provide details about population distribution and density that are critical for understanding demographic patterns.
A special purpose map can also overcome the limitations of standard maps, like the red-states-blue-states map, which may misrepresent the actual political landscape due to the varying population densities across the country. With over 75% of Americans living in urban areas, it is essential to visualize the concentration of populations in these areas, something a special purpose map focused on population density would best depict.