Many websites provide free lists of area codes, such as AllAreaCodes.com, Area-Codes.com and AreaCodeLocations.info. AllAreaCodes.com lists all U.S. area codes on a map of the United States. Area-Codes.com lists area codes by state. AreaCodeLocations.info lists area codes in numerical order.
Area-Codes.com also provides a search feature that allows users to find area codes using various options, including city, state and zip code. AllAreaCodes.com provides a Canadian area code map in addition to the U.S. map.
Phone companies use area codes to route calls to the proper switching office and complete phone call circuits. Phone companies introduced area codes in 1947 to replace human operators who physically moved wires from one switch to another in order to complete phone circuits.