Counties provide a variety of services to residents including law enforcement, adjudication, emergency management, health and human services, public works, economic development and much more. The Village of Bartlett is located in three counties. If you live north of Devon Avenue and east of Rt. 25 you live in Cook County. If you live south of Devon Avenue and east of Rt. 25 you live in DuPage County. If you live west of Rt. 25 you live in Kane County.