Table 3: The hierarchy of the 452 cities in USA and the related measures (2000).

Class City number ( )Average population size ( )Average urban area ( )

 1117799861.0008683.200
 2210048695.5004908.995
 344561564.5003923.070
 483335242.6252828.796
 5161690796.2501493.243
 632815564.656899.782
 764354537.344451.605
 8128156158.125217.896
 9(197)69740.228103.053

Source: The original data come from the US Census Bureau (2002.08.25), only the 452 US cities with population size more than 50,000 are available at the website: http://www.demographia.com/.
Notes: (1) The last class of each hierarchy is a lame-duck class. (2) The unit of population is “person”, and that of urbanized area is “square kilometers.”