There are nine time zones in the United States. The time zones are as follows:
| CODE | UNITED STATES TIME ZONE BOUNDARIES | UTC OFFSET |
| AST | ATLANTIC STANDARD TIME | UTC - 4 |
| EST | EASTERN STANDARD TIME | UTC - 5 |
| CST | CENTRAL STANDARD TIME | UTC - 6 |
| MST | MOUNTAIN STANDARD TIME | UTC - 7 |
| PST | PACIFIC STANDARD TIME | UTC - 8 |
| AKST | ALASKA STANDARD TIME | UTC - 9 |
| HAST | HAWAII-ALEUTIAN STANDARD TIME | UTC - 10 |
| SST | SAMOA STANDARD TIME | UTC - 11 |
| ChST | CHAMORRO STANDARD TIME | UTC +10 |
| Hawaii Time | Alaska Time | Pacific Time |
Hawaii Standard Time UTC -10:00 Honolulu | Alaska Standard Time UTC -09:00 Anchorage | Pacific Standard Time UTC -08:00 Los Angeles San Francisco Las Vegas Seattle |
| Mountain Time | Central Time | Eastern Time |
Mountain Standard Time UTC -07:00 Denver Phoenix | Central Standard Time UTC -06:00 Chicago Houston Dallas | Eastern Standard Time UTC -05:00 New York Washington DC Atlanta |