John Clark, a Mesoamericanist, notes, "If you found this [Cahokia] in the Mayan lowlands, there would be no doubt that this was a city. It would be in the top 10 of all Mesoamerican cities." That is a good way to describe the situation. We know the Mayas and Aztecs built cities, and no one would question the urban status of this site if it were located in Mesoamerica. But since it is in North America, where ancient native societies have generally been viewed as "less complex" than their cousins to the south, people need more convincing that Cahokia was, indeed, a city.
Now I don't know the demographic data for Cahokia and its hinterland, but I think the population density within the Cahokia urban center was probably HIGHER than within Maya cities, but the population density of the "Greater Cahokia" region was most likely lower than that of the Maya lowlands.
Maya cities had very low URBAN population densities (even compared to a sprawling modern city like Phoenix):
- Tikal (Maya): 600 persons per square kilometer
- New York City: 9,400
- Phoenix: 1,900
- Maya lowlands: 180 persons per sq. km
- New York State: 150
- Illinois: 80
- Arizona: 17
For more discussion of some of the issues of how archaeologists (and others) define cities, see some of my prior posts, What is a City? Definitions of the Urban, or Defining Cities and Urbanism (again).
Lawler, Andrew (2011) America's Lost City. Science 334:1618-1623.