<P> Area codes 847 and 224 are Illinois area codes covering northeastern Illinois and many northern suburbs of Chicago . They serve most of Lake County, the northern part of Cook County, the northern part of Kane County, and a small part of McHenry County . </P> <P> The main area code, 847, was created on January 20, 1996, in a three - way split from area code 708 . Within only five years, however, 847 was already close to exhaustion due to the explosive growth of the Chicago suburbs and the proliferation of cell phones and pagers . On January 5, 2002, area code 224 overlaid the 847 NPA and 10 - digit dialing was implemented . </P>

Where is area code 847 located in the united states