Polk County (Iowa) chart of communities by population (2010)

Reference 1: Population (2010 Census).

Reference 2: Des Moines, West Des Moines (partially in Dallas County), Ankeny, Urbandale (partially in Dallas County), Johnston, Clive (partially in Dallas County), Altoona, Norwalk (mostly in Warren County), Pleasant Hill, Grimes (partially in Dallas County), Windsor Heights, Carlisle (partially in Warren County), Bondurant, Polk City, Saylorville, Mitchellville (partially in Jasper County), Granger (partially in Dallas County), Elkhart, Runnells, Alleman and Sheldahl (partially in Boone and Story Counties).

Source: http://en.wikipedia.org/wiki/Polk_County,_Iowa