[Myrddin]

Using the sq km basis: Idaho (6), Bannock county (26.3), Chubbuck (1059). The high density is due to trailer parks used to pump up the city population to meet thresholds required for licensing bars. My neighborhood has minimum sq ft requirements for houses. They must be 3500 sq ft or larger. My lot is 1/3 acre. The immediate area is zoned "low density residential". Suffice to say there are some lovely houses on large lots contrasting with very high density trailer parks to achieve the "average".

[Dundee]

Well, Australia as a whole has around 3 per sq km but considering how heavily urbanized we are, once you get out of the capital cities the population density drops big time. The Northern Territory (520,901 square miles or 1,349,129 sq km) has a density (including the capital) of 0.15 per sq km and 0.07 outside of Darwin.