This relationship is important when analyzing data of different scales. The value of small-scale mapping is to show the population trends throughout the region. These boundary locations are not based on legal land descriptions, which could affect the size of a county and render the population density figures inaccurate for local analysis. The scale of the maps also affects accuracy. Exact boundary positions cannot be mapped in detail at this small scale.
Some geographic principles apply when comparing total population with population density.
The size of a county will affect how population density is shown when compared to total population. Given this situation, the population density remains in the high category through the decades, while total population remains in the middle category. When looking at the population density maps, the impression is that San Francisco is a highly populated place, but when looking at the total population it is not in the high category. The same is true for Denver County in Colorado. Its population density is in the high category, but its total population is in the middle category.