400-499
400: not used
401: Rhode Island (all)
402: Nebraska (Omaha, Lincoln, Norfolk, Superior, and most of eastern Nebraska)
- Originally covered all of Nebraska; split in 1954 to create 308.
- Overlain by 531 in 2011.
403: Alberta (Calgary, Banff, Red Deer, Medicine Hat, Lethbridge, Brooks, and most of southern Alberta)
- This area code formerly covered all of the Yukon Territory and part of the Northwest Territories. These were split off in 1997 to compose part of 867.
- Split in 1999 to create 780.
- All of Alberta (403 and 780) has now been overlain by 587.
404: Georgia: Atlanta and the Atlanta metropolitan area inside of the Interstate 285 perimeter highway
- This area code originally covered all of Georgia, but it was split to create Area code 912 in 1954; Area code 706 in 1992; and area code 770 in 1995. Area code 404 is now completely surrounded by area code 770, which forms an annulus around it.
- Overlain by 678 in 1998.
405: Oklahoma (Oklahoma City, Stillwater, Edmond, Norman, Shawnee, and most of central Oklahoma)
- Originally covered all of Oklahoma; split to create 918 in 1953 and 580 in 1997.
406: Montana (all)
407: Florida (Orlando, Sanford, St. Cloud, Kissimmee, and part of east-central Florida)
- Created in 1988 by split from 305.
- Split in 1996 to create 561.
- Split and overlain, partially, by 321 in 1999.
408: California (San Jose, Cupertino, Los Gatos, Milpitas, Mountain View, Santa Clara, Sunnyvale, and Silicon Valley)
- Created in 1959 by split from 415.
- Split in 1998 to create 831.
- Overlain by 669 as of November 20, 2012.
409: Texas (Beaumont, Galveston, Orange, Port Arthur, and Texas City.
- Created in 1983 by split from 713.
- Three-way split in 2000 created 936 and 979.
410: Maryland (except for St. Mary's County, all counties and cities which touch the Chesapeake Bay, the Atlantic Ocean, or Delaware, including Annapolis, metropolitan Baltimore, Berlin, Cambridge, Ocean City, Princess Anne, and Salisbury) as well as Howard County (Columbia).
- Created in 1991 by split from 301.
- Overlain by 443 in 1997.
- Overlain by 667 in 2012.
411: Directory Services; 1-areacode-555-1212 is also used to reach directory services in areas other than the caller's own area code.
412: Pennsylvania (Pittsburgh region, including McKeesport, Monroeville, Bethel Park, Penn Hills, and Ross; the area code encompasses the majority of Allegheny County and portions of Westmoreland County)
- Split in 1998 to create 724.
- Overlain by 878 in 2001.
413: Massachusetts (Springfield, Pittsfield, Holyoke, Greenfield, and most of Western Massachusetts)
414: Wisconsin (Milwaukee County and the city of Milwaukee)
- Split in 1955 to create part of 608.
- Split to create 920 (1997) and 262 (1999).
415: California (San Francisco and most of Marin County)
- Split in 1959 to create 408 and 707.
- Split in 1991 to create 510.
- Split in 1997 to create 650.
416: Ontario (the City of Toronto)
- Split in 1953 to create part of 519.
- Split in 1993 to create 905.
- Overlain by 647 in 2001.
- Overlain by 437 in 2013.
417: Missouri (Springfield, Joplin, Branson, Lamar, Lebanon, and most of southwestern Missouri)
- Created in 1950 from parts of the area codes 314 and 816.
418: Quebec (Quebec City, Saguenay, the Gaspé Peninsula, Côte-Nord, Chibougamau, St-Georges), Maine (Estcourt Station)
- Overlain by 581 in 2008.
419: Ohio (Toledo, Sylvania, Mansfield, Lima, Findlay, Sandusky, Bowling Green, and most of northwestern Ohio)
- Overlain by 567 in 2002.
420–422: not used
423: Tennessee (two discontiguous portions of East Tennessee: Bristol, Johnson City, Kingsport, etc., in the northeast; and Chattanooga, Cleveland, Philadelphia, and McMinnville in the southeast
- Created in 1995 by split from 615.
- Split in 1999 to create 865.
424: California
- Overlain on 310 in Los Angeles County in 2006.
425: State of Washington (the northern and eastern suburbs of Seattle: Bellevue, Everett, Edmonds, Kirkland, Redmond, Renton, Sammamish, Issaquah, and Lynnwood.)
- Created in 1997 by split from 206.
426–429: not used
430: Texas
- Overlain on 903 in 2003.
431: Manitoba. Will overlay 204 and be active beginning November 2012.
432: Texas (West Texas: Midland, Odessa, Big Spring, Alpine, Fort Stockton.
- Created in 2003 by split from 915.
433: not used
434: Virginia (Charlottesville, Lynchburg, Danville, and south-central Virginia)
- Created in 2001 by split from 804.
435: Utah (Cedar City, Logan, Moab, Park City, Price, St. George, Tooele, Vernal and all the rest of Utah, excluding the counties of Davis, Morgan, Salt Lake, Utah, and Weber)
- Created in 1997 by split from 801.
436: not used
437: Province of Ontario: Toronto metropolitan area
- Reserved for use as an overlay on 416 and 647. Scheduled to come into effect on March 25, 2013.
438: Province of Quebec: Montreal metropolitan area
- Overlain onto 514 in 2006.
439: not used
440: Ohio (surrounding Cleveland on three sides, including: Elyria, Lorain, Oberlin, Ashtabula, and most of north-central Ohio)
- Created in 1997 by split from 216.
441: Bermuda (all)
- Created in 1995 by split from 809.
442: California
- Overlain onto 760 in 2009.
443: Maryland
- Overlain onto 410 in 1997, mostly for the use of cellular telephones
444: not used
445 was formerly assigned to overlay 215 and 267 (Philadelphia, Pennsylvania), but this number is no longer assigned for any location. (One thousands block is assigned to a switch in Tucson Arizona.)
446: not used
447: Illinois
- Proposed overlay onto 217.
448–449: not used
450: Quebec (central southern Quebec including the city of Laval and other suburbs of Montreal but excluding the City of Montreal)
- Created in 1998 by split from 514.
- Overlain by 579 in 2010.
451–455: not used
456: Inbound international calls for carrier-specific services
457: not used
458: Oregon (Eugene, Medford, Bend, Pendleton, Corvallis, Ontario, Burns, and all of Oregon except the metropolitan region of northwestern Oregon)
- Overlain on 541 in 2010.
459–463: not used
464: Illinois
- Proposed overlay for 708.
465–468: not used
469: Texas
- Overlain on 214 and 972 in 1999.
470: Georgia: An overlay onto Area code 404, area code 678, and Area code 770
- Activated in 2010.
471–472: not used
473: Grenada (all)
- Created in 1997 by split from 809.
- Mnemonic: GRE or GRD
474: not used.
475: Connecticut
- Overlain onto 203 in 2009.
476–477: not used
478: Georgia (Macon, Warner Robins, Swainsboro, Milledgeville, Perry, and part of central Georgia)
- Created in 2000 by split from 912.
479: Arkansas (Fort Smith, Fayetteville, Rogers, and most of northwestern Arkansas)
- Created in 2002 by split from 501.
480: Arizona (Mesa, Scottsdale, Chandler, Tempe, and the eastern Phoenix metropolitan area)
- Created in 1999 by split from 602.
481–483: not used
484: Pennsylvania
- Overlain on 610 in 1999.
485–489: not used
490–499: Reserved for potential North American Numbering Plan expansion
Read more about this topic: List Of North American Numbering Plan Area Codes