What are the US area codes for telephones?

There are about 300 area codes currently in use in the United States. The exact number depends whether you include U.S. territories like Guam and Puerto Rico, and whether you include non-geographic codes like 800/888/877/866/855 toll-free.

There are approximately 275 geographic area codes in use in the United States, and 13 which are not assigned to any particular area. Several states have only one area code assigned to them, while California has the most with 31.