How many timezones are there in the United States?
Time Zone Map of the United States showing the six US timezones. Idaho uses Pacific Time in the northern panhandle, north of the Salmon River, and Mountain Time in south. Indiana, most of state observes Eastern Time except for the northwestern and south western corners which use Central Time.
How wide is a 1 hour time zone?
Time Zone Borders Vary. Theoretically, each 1-hour time zone is 15 degrees wide, indicating a 1-hour difference in mean solar time. This can be seen as the white and gray stripes on our Time Zone Map and in the image above.
What is a time zone?
A time zone is a region of the globe that observes a uniform standard time for legal, commercial, and social purposes. Time zones tend to follow the boundaries of countries and their subdivisions because it is convenient for areas in close commercial or other communication to keep the same time.
Is the time zone map always current?
Our Time Zone Map is always current. At timeanddate.com we define a time zone as a region where the same standard time is used. The local time within a time zone is defined by its offset (difference) from Coordinated Universal Time (UTC), the world's time standard.
What is ISO 8601?
ISO 8601 is a standard established by the International Organization for Standardization defining methods of representing dates and times in textual form, including specifications for representing time zones.
How did railroads use time?
Timekeeping on North American railroads in the 19th century was complex. Each railroad used its own standard time, usually based on the local time of its headquarters or most important terminus, and the railroad's train schedules were published using its own time . Some junctions served by several railroads had a clock for each railroad, each showing a different time.
What is the Greenwich Mean Time?
The Royal Observatory, Greenwich, founded in 1675, established Greenwich Mean Time (GMT), the mean solar time at that location, as an aid to mariners to determine longitude at sea, providing a standard reference time while each location in England kept a different time.
Why do we draw time zones?
One reason to draw time zone boundaries far to the west of their ideal meridians is to allow the more efficient use of sunlight. Some of these locations also use daylight saving time (DST), further increasing the difference to local solar time. As a result, in summer, solar noon in the Spanish city of Vigo occurs at 14:41 clock time. This westernmost area of continental Spain never experiences sunset before 18:00 clock time, even in winter, despite lying 42 degrees north of the equator. Near the summer solstice, Vigo has sunset times after 22:00, similar to those of Stockholm, which is in the same time zone and 17 degrees farther north. Stockholm has much earlier sunrises, though.
How long is the Sun in the sky?
This variation corresponds to four minutes of time for every degree of longitude, so for example when it is solar noon in London, it is about 10 minutes before solar noon in Bristol, which is about 2.5 degrees to the west.
What is the offset of time zones?
All time zones are defined as offsets from Coordinated Universal Time (UTC), ranging from UTC−12:00 to UTC+14:00. The offsets are usually a whole number of hours, but a few zones are offset by additional 30 or 45 minutes, such as in India and Nepal .
Why do time zones follow longitude?
Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
What does it mean to be in the same time zone?
It means that in each geographic region within a time zone people use the same time. All these zones are defined by an offset from the Coordinated Universal Time (UTC; see below) by a number of hours (UTC−12 to UTC+14) centered on the prime meridian (0°; since 1884 the Greenwich meridian [ 1] ).
What is the time zone?
What is a time zone? A time zone is ideally one of 24 spherical lunes (section on the globe in a north/south direction) with equal-width, each assigned with one of the 24 hours (one day).
Why do we use time zones?
Modern use of time zones tend to follow the boundaries of countries and their subdivisions instead of standard parallels, because it is convenient in close economical, political areas to keep the same time. U.S. Time Zones. The Map below is shows the six time zones of the United States and the actual time in the different time zones.
What is UTC time?
UTC: Coordinated Universal Time . Time zones around the world are expressed as positive or negative offsets from UTC or GMT (arguably the same as Coordinated Universal Time ). Local time is UTC plus the time zone offset for that location, e.g.: Eastern Standard Time (EST) = UTC -5 hours.
Which states use Eastern Time?
5. Indiana, most of state observes Eastern Time except for the northwestern and south western corners which use Central Time. 6. Kansas, most of state use Central Time, some counties in west observe Mountain Time.
When did UTC replace Greenwich Mean Time?
UTC replaced Greenwich Mean Time on 1 January 1972 as the basis for the main reference time scale or civil time in various regions. As you can see on the map, there are several US states split by time zones. 1. Alaska observes Alaskan Time, Aleutian Islands west of 169° 30’ west observe Hawaii-Aleutian Time. 2.
Which states do not observe DST?
Arizona does not observe DST, except for the Navajo Nation in the north eastern corner. 3. Florida uses Central Time in the western panhandle, and Eastern Time in the rest of the state. 4. Idaho uses Pacific Time in the northern panhandle, north of the Salmon River, and Mountain Time in south.
What is the time zone?
The term time zone can be used to describe several different things, but mostly it refers to the local time of a region or a country.
How many time zones are there in the world?
If each time zone were 1 hour apart, there would be 24 in the world. However, the actual borders on the time zone map have been drawn to match up with both internal and international borders, and rarely match up exactly with the 15-degree longitudes. Also, the International Date Line (IDL), creates 3 time zones and several time zones are only 30 and 45 minutes apart. This makes the total number of time zones worldwide much higher.
What is daylight saving time?
Daylight Saving Time Zones. Regions that use Daylight Saving Time (DST) change the time zone name and time during the DST period. The words “daylight” or “summer” are then usually included in the time zone name. The areas that don't use DST remain on standard time zone all year. For example, California uses Pacific Daylight Time (PDT) ...
What time zone does California use?
The areas that don't use DST remain on standard time zone all year. For example, California uses Pacific Daylight Time (PDT) during the DST period, but Pacific Standard Time (PST) during the rest of the year.
How long does UTC change?
UTC time changes 1 hour forward and backward corresponding to a 1-hour difference in mean solar time for every 15 degrees east or west of the prime meridian (0° longitude) in Greenwich, London, United Kingdom. The offset is expressed as either UTC- or UTC+ and the number of hours and minutes.
What time zone has the same abbreviation?
For example, India Standard Time (IST) and Israel Standard Time (IST) have the same abbreviation, but completely different UTC offsets of UTC+5:30 and UTC+2:00.
Why are there 25 military time zones?
The reason there are 25 military time zones instead of 24 is that Mike Time Zone (M) and Yankee Time Zone (Y) are the same time, but on either side of the International Date Line.
What time zone is Alaska?
All of these time zones have standard time zones that are offset from UTC from UTC-04:00 through UTC+10:00, though some additionally observe daylight saving time (DST).
What is daylight saving time?
Many countries or regions, especially those in Europe and North America practice daylight saving time (DST), sometimes referred to as "summer time," with the intent of saving energy. This typically involves advancing the time on a clock by one hour in early spring, and "rolling back" the time in autumn.
What is the UTC offset?
UTC offset can range from UTC-12:00 to UTC+14:00.
What time zone is the eastern part of the United States?
These time zones encompass most of the contiguous United States. Eastern Time Zone (ET): UTC-05:00 – includes 22 states in the eastern part of the contiguous United States, including some parts of Canada, Mexico, Panama, and the Caribbean islands.
How many states are in the Central Time Zone?
Only 9 states are fully within the Central Time Zone. Eleven are shared with either the Mountain Time Zones or the Eastern Time zones. Mountain Time Zone (MT): UTC-07:00 – includes parts of Canada, Mexico, and the U.S. 5 states are fully within the MT, Ten are shared with either the Pacific Time Zone or the Central Time Zone.
What is the time zone?
What is Time Zone. A time zone is a region on Earth that uses a uniform time. They are often based on boundaries of countries or lines of longitude. Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory located in Greenwich, London, considered to be located at a longitude of zero degrees.
What is the Pacific Time Zone?
Pacific Time Zone (PT): UTC-08:00 – includes parts of Canada, the western U.S., and western Mexico. California and Washington are fully within PT. Three states are split between the Pacific Time Zone and the Mountain Time Zone, and Alaska is split between the Pacific Time Zone and Alaska Time Zone.
What is the time zone for daylight savings time?
During Daylight Saving Time (DST) the time zone name and time changes. The words “daylight” or “summer” are then usually included in the name, and the local time is usually set forward 1 hour. For example, California uses Pacific Daylight Time (PDT) during the DST period with a UTC offset of UTC-7, but Pacific Standard Time (PST) ...
What is the offset of Pacific Standard Time?
For example, California uses Pacific Daylight Time (PDT) during the DST period with a UTC offset of UTC-7, but Pacific Standard Time (PST) with an offset of UTC-8 during the rest of the year.
How many time zones are there in the world?
If each time zone were 1 hour apart, there would be 24 in the world. But several time zones have only 30 and 45 minutes offsets, making the total number worldwide much higher.
How wide is the time zone?
Theoretically, each 1-hour time zone is 15 degrees wide, indicating a 1-hour difference in mean solar time. This can be seen as the white and gray stripes on our Time Zone Map and in the image above.
How many people would be in the world if each time zone was 1 hour apart?
If each time zone were 1 hour apart, there would be 24 in the world.
What is the time zone in California?
The reason it may be confusing is that California's local time during DST is UTC-7, but the standard time in California is UTC-8. However, Arizona's local time is always UTC-7, because there's no DST in Arizona, and they remain on standard time all year.
How many hours ahead of UTC is 75 degrees?
At 75 degrees east (or 75° E) longitude, the time would be 75 degrees divided by 15 degrees = 5 hours ahead of UTC, or UTC+5. Below are all the different local times currently in use worldwide.
What time is daylight savings time in Alaska?
Alaska 11:31 PM Hawaii 9:31 PM Pacific 12:31 AM Mountain 1:31 AM Central 2:31 AM Eastern 3:31 AM. Daylight Saving Time, for the U.S. and its territories, is NOT observed in Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and the state of Arizona (not the Navajo Indian Reservation, which does observe DST).
When does standard time end in 2022?
Standard Time ends: March 13, 2022 02:00 local time. Clocks go forward one hour.
How Many Time Zones Are There in the US?
There are 9 time zones by law in the USA and its dependencies. However, adding the time zones of 2 uninhabited US territories, Howland Island and Baker Island, brings the total count to 11 time zones.
What is the generalized time zone?
The time zones in the contiguous US are often referred to by their generic name, without making a difference between standard time and Daylight Saving Time designations. For example, Eastern Time (ET) refers to Eastern Standard Time (EST) or Eastern Daylight Time (EDT), depending on which is currently in use.
What is the 12th time zone?
Since Howland Island and Baker Island constitute the world's westernmost landmasses in relation to the International Date Line, making them the last places on Earth where any date exists, they are sometimes assigned a theoretical 12th time zone called Anywhere on Earth (AoE).
Which states have their own time zones?
In addition, Alaska, Hawaii, and 5 US dependencies all have their own time zones. As neither Hawaii nor the 5 dependencies use Daylight Saving Time (DST), there are only 6 corresponding DST time zones.
Which states don't use daylight savings time?
Almost all states in the US use Daylight Saving Time (DST). Most of Arizona and Hawaii don't use DST. Indiana introduced DST in 2006.
When was the US divided into 4 time zones?
The United States' Time Zone History. The US was divided into 4 standard time zones on November 18, 1883, and jurisdiction for the zones was given to the Interstate Commerce Commission (ICC). Since 1967, the US Department of Transportation (DOT) has been responsible for governing time zones in the country. Time zones in the USA are defined in the ...
