How many U.S. states have one and only one area code?

In the USA a few states have only one area code such as Alaska, Delaware, Hawaii, Idaho, Maine, Montana, New Hampshire, North Dakota, Rhode Island, South Dakota, Vermont, West Virginia and Wyoming.

The states using the most area codes are Texas which is currently using 24 area codes, California 26 area codes, Florida 16 area codes, and New York 14 area codes.

http://www.areacodehelp.com/acus/us_area_codes.shtml

All the states of Australia have only one area code for land line calls.

http://www.accesscomms.com.au/reference/areacode.htm

02 New South Wales
02 Australian Capital Territory
03 Victoria
03 Tasmania
07 Queensland
08 South Australia
08 Northern Territory
08 Western Australia

13 States + DC

Alaska 907
Delaware 302
Hawaii 808
Idaho 208
Maine 207
Montana 406
New Hampshire 603
North Dakota 701
Rhode Island 401
South Dakota 605
Vermont 802
West Virginia 304
Wyoming 307

District of Columbia 202

http://tinyurl.com/gzljj
indiatraveltimes.com/telephone_area_codes/u
s_telephone_areacode_listing_byplaces.html

Update: West Virginia now has two area codes (304, 681).

A few states have only one area code such as Alaska, Delaware, Hawaii, Idaho, Maine, Montana, New Hampshire, North Dakota, Rhode Island, South Dakota, Vermont, and Wyoming.

http://www.areacodehelp.com/acus/us_area_codes.shtml