Peoria is the seat of Peoria County and the center of an urban complex consisting of Peoria Heights, West Peoria, Bartonville, Bellevue, East Peoria, Creve Coeur, and Pekin. The city is considered the oldest continuously inhabited American community west of the Allegheny Mountains. Another of Peoria's distinctions is its typicality: in terms of such demographic characteristics as median age and purchasing patterns, the city's general makeup is almost identical to that of the United States as a whole, thus making it an ideal test market for consumer researchers.