LincMad’s Telephone Area Code Map of North America is a pretty useful tool to bookmark for reference if you need to call or identify people across the country. The tables are a little more obscure than necessary, but still it’s a nice resource.
This map shows all telephone area codes in use as of 2007-02-22 in the United States and Canada. Area codes that have not yet taken effect are shown with a green line and the area code in parentheses. Some planned area codes that have been cancelled or indefinitely postponed are no longer shown…Detailed maps of some of the metropolitan areas may be added in the future, along with time-zone boundaries. All boundaries shown are approximate.