List of North American Numbering Plan area codes
Code Territory or use Notes
300 not in use easily recognizable code ( ERC )
301 Maryland ( Silver Spring , Washington , D.C. , suburbs , all counties which touch the Potomac River ; Hagerstown , Frederick , Rockville , Cumberland , and land line telephones in western Maryland ) originally covered all of Maryland 1991 , split to create 410 1997 , overlaid by 240 to be overlaid with 227 in the future
302 Delaware ( all )
303 Colorado ( Denver , Boulder , Longmont , Aurora , Golden , Limon , Littleton , Centennial ; central Colorado ) originally covered all of Colorado 1988 , split to create 719 1995 , split to create 970 1998 , overlaid by 720
304 West Virginia 2009 , overlaid by 681
305 Florida ( all of Miami-Dade County and the Florida Keys ) originally covered all of Florida 1953 , split to create 813 1965 , split to create 904 1988 , split to create 407 1995 , split to create 954 1998 , partially overlaid by 786 in Miami-Dade County only 2008 , completely overlaid by 786 , including the Florida Keys
306 Saskatchewan 2012 , overlaid by 639 To be overlaid by 474 on October 2 , 2021 ; implementation date to be announced soon
307 Wyoming ( all )
308 Nebraska ( North Platte , Scottsbluff , McCook , Kearney , Grand Island ; western Nebraska ) 1954 , created by a split from 402
309 Illinois ( Peoria , Bloomington , Moline , Rock Island , Galesburg ; west-central Illinois ) 1957 , created from parts of 217 and 815
310 California ( southwestern coastal and coastal-adjacent areas of Los Angeles County , including Beverly Hills , Brentwood , Malibu , Pacific Palisades , Redondo Beach , Santa Monica and Torrance , as well as Santa Catalina Island ) 1991 , created by a split from 213 1997 , split to create 562 2006 , overlaid by 424
311 Not an area code - used for non-emergency calls to local government , or to reach the city or county hall in some localities
312 Illinois ( downtown Chicago ) 1989 , split to create 708 1996 , split to create 773 2009 , overlaid by 872
313 Michigan ( Dearborn , the Grosse Pointes ; Detroit and its enclaves of Hamtramck and Highland Park ) 1993 , split to create 810 1997 , split to create 734 to be overlaid with 679 in the future
314 Missouri ( St. Louis , St. Louis County , Florissant , Crestwood , Hazelwood , Kirkwood , and surrounding suburbs of St. Louis ) 1950 , split to create a part of 417 1996 , split to create 573 1999 , split to create 636
315 New York ( Syracuse , Utica , Watertown ; north-central New York ) 1954 , split to create a part of 607 2017 , overlaid with 680
316 Kansas ( Wichita metropolitan area , McConnell Air Force Base , Augusta , El Dorado , Mulvane , and Hutchinson ) 2001 , split to create 620
317 Indiana ( Indianapolis and immediate metro area including Carmel , Fishers , Noblesville , Westfield , Greenwood , Mooresville , Beech Grove , Plainfield , Avon , Brownsburg , and Zionsville ) 1948 , split to create 219 1997 , split to create 765 2016 , overlaid with 463
318 Louisiana ( Shreveport-Bossier City , Monroe , Alexandria , Fisher , Tallulah , and most of northern Louisiana ) originally used temporarily for the San Francisco Bay Area until 1953 . 1957 , created by a split from 504 1999 , split to create 337
319 Iowa ( Cedar Rapids , Waterloo , Burlington , Iowa City ; parts of eastern Iowa ) 2001 , split to create 563
Area codes in numerical order -- 300–399
The North American Numbering Plan (NANP) divides the regions of its member nations (primarily in North America, including the Caribbean) into geographic numbering plan areas (NPAs). Each area is assigned a three-digit area code which is prefixed to each telephone number issued in its service area. Some areas are assigned multiple codes in an overlay plan. The rules for numbering NPAs do not permit the digits 0 and 1 as the leading digit, which also applies for central office codes. 0 has been used traditionally for operator-assisted telephone calls, and the digit 1 was traditionally ignored in switching equipment as a leading digit, because it could not be distinguished reliably from intermittent loop disconnections. NPAs with 9 as the second digit are reserved for future format expansion. Area codes with the last two digits matching, such as 322 and 800, are considered easily recognizable codes (ERC), where the series of 8xx are used for toll-free services.