Area Code 314 January 18, 2021 allcitycodes Telephone Codes 0 Where is area code 314 located? Below you will find a list of all cities covered by area code 314 in Missouri. Bridgeton, MO Earth City, MO Glencoe, MO Hazelwood, MO Maryland Heights, MO Saint Ann, MO Valley Park, MO Read more:Area Code 718Area Code 815Area Code 810Area Code 816Area Code 812Area Code 804Area Code 813Area Code 715Area Code 770Area Code 719