312 Area Code, Illinois

312 area code is a telephone area code in the North American Numbering Plan (NANP) for Chicago in the state of Illinois, United States. The area code is one of the original area codes created in 1947 and covered all of the Chicago metropolitan area (downtown area) in the county of Cook.

Area Code312
Major CityChicago
Service Date01/01/1947
Time ZoneCentral
Overlay Complex312/872
LocationIllinois (IL)
CountryUnited States

The main post offices in each region in Nigeria have postal codes ending in 0001. The lowest postal code is 100001 and the highest with a special code is 982112.

NIPOST or Nigerian Postal Service is a company owned and operated by the government of this country. The country has a total of more than 5000 post offices spread throughout the region. Find the correct ZIP (Zone Improvement Plan) code or Postal Code for the postal address you need.