Talk:Time in the United States

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Yamara 16:23, 23 June 2008 (UTC)

Naming format[edit]

Can contributors to this article please check out and comment on regarding article names? -- Chuq 04:44, 19 October 2005 (UTC)

edits for calarity[edit]

I've edited the descriptions of the rough Eastern Time Zone & Central Time Zone in an attempt to make them more clear by using natural regions. I've also edited the boundary descriptions for clarity. Most importantly, most of East Tennessee is in the Eastern timezone, which is generally regarded as Tennessee east of the easternmost cross of the Tennessee River with a minor adjustment to keep Hamiliton County (Chatt.) entirely in Eastern Tennessee dispite the bit of the county on the wrong side of the river. In addition, a couple of counties in NE Middle Tennesee may also be in the EST. Jon 18:41, 26 June 2006 (UTC)

State Option on Daylight Savings Time Section[edit]

It may be worth noting that in 2007, the start date for DST is being moved up to 2nd Sunday of March and the end date to 1st Sunday in November. Also, at some point the now old Indiana exception should be sniped. There's another article on history of Indiana Timezones. Jon 18:46, 26 June 2006 (UTC)

The key point that the section might make is that DST isn't observed everywhere. — Preceding unsigned comment added by (talk) 17:11, 13 June 2012 (UTC)

Future years porition of chart[edit]

It may be premature to list starting with 2008 because the extenstion of daylight savings time for 2007 included an energy study to compare energy use in the extended portions of daylight savings time was the prior year with a statement saying if energy isn't saved they'd revert (see the conference report for the 2005 Energy bill). This is further complicated by past congresses can not be legally bound the current congress to do anything along with the change of control of congress since then. Jon 13:55, 18 June 2007 (UTC)

  • Partially Disagree. Congress can always rescind a law passed by a previous Congress, so what? The law as it stands prescribes the dates shown in the chart. When DST was extended, the wire services carried tables showing "Daylight Savings Time Schedules for the next six years". This is good encyclopedic information, which people consult for planning purposes in scheduling future events, work schedules, timetables, etc., many of which are prepared years ahead of time. (Right now, for example, I'm working on a convention scheduled for Nov., 2010). OTOH, I'd agree with you that the chart probably shouldn't go into the future as far as 2017 and should be annotated, "subject to review pursuant to the Energy bill..." JGHowes talk - 14:27, 18 June 2007 (UTC)
  • I've edited this section to take account of the 2008 review JGHowes talk - 11:57, 24 June 2007 (UTC)

Switch from GMT to UTC as basis[edit]

This is fairly trivial, but it should be noted that standard time zones in the US have always been based upon mean solar time (GMT), until the passing of Public Law 110-69 on 2007-08-09, where it has been changed to be based upon (the US's interpretation of) UTC. See Bill H.R. 110-2272. -- Dmeranda 20:44, 20 August 2007 (UTC)

Thanks for the citation. The specific change is in Title III Sec. 3013. — Joe Kress 21:38, 20 August 2007 (UTC)

Place vs. Time[edit]

Can we please distinguish between a time zone and a time offset somehow? --Uncle Ed 02:48, 18 October 2007 (UTC)

Capitalization of the names of time zones[edit]

If one looks at the text of the law, 15 USC § 263. Designation of zone standard times, it seems that the capitalization rules used follow standard English: proper nouns are capitalized, other words are not. Thus the law refers to "eastern standard time", not "Eastern Standard Time". Also even for proper nouns, only the first word is capitalized so you have "Atlantic standard time" and not "Atlantic Standard Time". Should this be corrected here, and on other articles that refer to the names? -- Dmeranda 17:16, 22 August 2007 (UTC)

Naming of the zones, again[edit]

Regarding the recent cleanup attempts to reduce link renaming (pipes), it should be observed that the resulting list of names is not consistent and probably not correct. For example we have "Central Time Zone (North America)" and "Mountain Standard Time" which certainly are not consistently named, and neither is correct; which is what the text in the article immediately preceding the list promises: "Only the full time zone names listed below are official..." Looking at Public Law 15 U.S.C 263[1] is the definitive source for the correct names to use. It starts with "The standard time of the first zone shall be known and designated as..." and continues to provide the following names (notice the capitalization used as well):

  1. Atlantic standard time
  2. eastern standard time
  3. central standard time
  4. mountain standard time
  5. Pacific standard time
  6. Alaska standard time
  7. Hawaii-Aleutian standard time
  8. Samoa standard time
  9. Chamorro standard time

So those are the names of the standard time in the various zones. Although the law never explicitly names the nine zones (it just uses ordinals, "first zone", "second zone", etc.), the best we can infer is that the definitive name for the zone would be the name of the corresponding time with the word "zone" appended; so for example the third zone would be called "central standard time zone", and the time within that zone is explicitly called "central standard time". It would not be right to drop the word "time", it is after all a "time zone", not some unqualified "zone". Also it would not be correct to drop the word "standard", as the law only ever uses "standard time" and not just "time". It is also worth noting that the law never uses the term "daylight" for the daylight saving time period—it in fact explicitly states that the time during the summer should also be called the "standard time", but just with it shifted by an hour. Admittedly, names like "Central Daylight Time" or "Central Time Zone" are indeed widely used, but they are colloquial (not to mention mis-capitalized) and are not normative as "central standard time zone" would be. -- Dmeranda 06:30, 18 October 2007 (UTC)

Thanks for taking the initiative to clear this up. I'm hoping to go even further, and provide proper names for time ZONES and time OFFSETS for America, as well as the rest of the world. I wish Wikipedia to be the definitive source of information on time zones, daylight savings time, etc.
When you want to know what time it is in a place far from you, wouldn't it be nice if Wikipedia could tell you? --Uncle Ed 15:01, 19 October 2007 (UTC)
The names "eastern standard time zone", etc., including "Samoa standard time zone", are so named in Standard Time Zone Boundaries 49CFR71, an external link I added long ago. Although these are regulations rather than laws, they are official. — Joe Kress 07:41, 20 October 2007 (UTC)


What happens at the boundaries? If you're on a train is there an announcement telling you to change your watch? If you drive are there signs by the side of the road? If so, can we have a picture of a representative example? (talk) 12:52, 21 January 2008 (UTC)

As far as I'm aware from my travels across the US, I have never seen any such signage or announcements on public transportation. If it exists it is atypical. -- Dmeranda (talk) 17:17, 21 January 2008 (UTC)
Thanks for answering. That's interesting because until I looked at this article I'd assumed the boundaries followed state lines, but as in many cases they don't, are you just meant to know when you've entered a new time zone on crossing into a different county or something? I've got another unrelated question. For TV scheduling purposes in the USA, pages like this say that times are listed in ET/PT. For something like the main news bulletins then, does Dan Rather or whoever it is these days present more or less the same thing twice to different audiences, unless there have been developments in what's being reported, or is it live for the east coast and then shown recorded three hours later on the west coast, or is it broadcast simultaneously across the country, meaning that for example the 9 o'clock news on the east coast is the 6 o'clock news on the west coast? I asked someone this once and they didn't seem to know. (talk) 17:41, 21 January 2008 (UTC)
This is not a definitive answer (if one even exists), but just an observation from a US citizen... Generally within the coterminous US, and possibly including Caribbean territories, national television programs are often repeated on hour offsets, with the original broadcast in the Eastern, and proceeding in turn through the Central, Mountain, and Pacific. I'm not sure what is done for Alaska and Hawaii though, due to their extreme western position. Of course this can vary from station to station and program to program. Sometimes programming may be played simultaneously in bordering time zones (for example "7 Eastern/6 Central", but then mountain and pacific may be played with a delay). For your "ET/PT" example that would mean that Eastern, Central, and Mountain would all be simulcast "live", but that Pacific viewers would see the show delayed. Programs which must be timely, for example national news during times of crisis or tragedy, may be either completely new for each zone, or rebroadcast with updates. Programs which require time-limited call-in voting (like many reality contest shows) may either be simultaneously broadcast in all zones, or rebroadcast in each zone combined with telephone-location data to prevent voting cross-zones. Sports games (Baseball/American Football) are usually simulcast live in all time zones without any zone-induced delays. And then you have the "cable/satelite" 24-hour programming (like CNN), which are for the most part simultaneously broadcast). There really is no single set standard though; although if anybody has any more definitive information please reference it. -- Dmeranda (talk) 23:14, 21 January 2008 (UTC)
Thanks a lot, that's all interesting. The only thing I could remember being sure of when I visited the USA was that baseball games and the like were simulcast as you said, billed as "10pm ET / 7pm PT" or whatever. I'd always been puzzled about how certain other time-sensitive broadcasts were done. I wonder if there is room for an article (or discussion over various articles perhaps because it might be too vague a topic for a specific article) on the practices of TV networks that operate over multiple time zones. This would be getting off topic for this page, but if anyone knows of discussion in Wikipedia of TV broadcasts over multiple time zones in other countries and how it's dealt with, I'd be interested to read it. (talk) 01:34, 22 January 2008 (UTC)
I partially disagree with Dmeranda. Virtually all broadcast network television programs are simulcast in the Eastern and Central time zones. Prime time in the Eastern zone is 8-11 pm with local or syndicated programming 7-8 pm, and the national news at 6:30-7 pm, whereas prime time in the Central zone is 7-10 pm with local and syndicated programming 6-7 pm and the national news at 5:30-6 pm. The Mountain zone schedule matches that of the Central zone, hence is one hour later, so its national news is original, or would be original if breaking news warranted it. The Pacific zone schedule matches that of the Eastern zone, hence is three hours later, so again its national news is original, or would be original if breaking news warranted it. Compare the TV listings for New York's ABC7, the TV listings for Chicago's ABC7, the TV listings for Denver's ABC7, and the TV listings for Los Angeles' ABC7. All Anchorage programming is by satellite, including live programming from New York and Pacific television sources. The Honolulu schedule matches the Eastern zone, hence is five hours later, but I doubt that its national news is original. See the TV listings for Honolulu ABC4. San Juan programming is via satellite or cable, obviously in Spanish, using the eastern prime time schedule of 8-11 pm, hence is one hour earlier. I have no idea how national new casts are handled in Puerto Rico. — Joe Kress (talk) 12:22, 22 January 2008 (UTC)
As far as public transportation, airplane pilots usually announce the local time when the plane lands, whether or not you've changed time zones. But, I don't remember any such announcements when I traveled cross-country on a train. Schoop (talk) 19:13, 4 March 2009 (UTC)
If your driving along an Interstate highway, there are generally signs saying when you've changed timezone boundaries reading something like "Entering [Name of new timezone]". If your flying, weather you've changed timezones or not there will be an annoucement on what local time is at the destination peroidically thruout the flight. As to any other public transit that crosses time zone lines, I've never done that. Jon (talk) 18:15, 20 May 2009 (UTC)
Another driving drive, prior to Indiana offically observing daylight sayings time, there was no sign when crossing from a county that didn't observe daylight savings time into a county that (unoffically) did. You just had to know which counties did if you didn't want to be an hour late / early. Jon (talk) 18:17, 20 May 2009 (UTC)

Olson Zoneinfo[edit]

I removed a table that had no explanation regarding the column meanings, the origin of the data, or what "Olson Zoneinfo" even was. I added a link to the main zoneinfo list page. Hopefully that satisfies whoever posted it originally. (talk) 15:57, 4 March 2009 (UTC)

Worth mentioning longitude?[edit]

I am wondering if it is worthwhile to add more details on the relationship between the time zones and longitude.

E.g., Everyone who observes eastern time sets their clocks to the local mean time for 75 degrees west longitude (i.e., UTC - 5 hours) during the "standard" period and to the local mean time for 60 degrees west longitude (i.e., UTC - 4 hours) during the "daylight saving time" period.

Likewise, for " Boundaries between the zones".

E.g., The nominal boundary between eastern time and central time is 82.5 degrees west longitude. The legal boundary runs as follows:

Bill_Starr (talk) 15:44, 17 March 2010 (UTC)

More time zones[edit]

Wake Island is GMT+12 and Baker Island and Howland Island are GMT-12. I don't know what their time zones are officially called, but I think it's worth mentioning the easternmost/westernmost or earliest/latest time zones and the fact that it can simultaneously be noon today and noon yesterday in the United States. Also, the US seems to have the greatest number of time zones and the greatest span of official times.

In Wikipedia, there is an article called Wake Island Time Zone but no official source is cited for that name. Maybe there is a military decree specifying that name; I don't know. In any event, that time zone is not specified by Title 15, Chapter 6(IX) which purports to set out all time zones for the United States and its possessions. As for Baker Island and Howland Island, the Wikipedia articles state that no time zone is specified. Citefixer1965 (talk) 23:11, 11 May 2010 (UTC)

External links[edit]

The USNO link needs updating.

Also, it should be noted that the proper definition of Time Zone is that it relates only to Winter or Standard time, as indicated by USNO; DST is irrelevant. Usage in Wikipedia has commonly been incorrect. (talk) 10:00, 29 September 2010 (UTC)

Another crack at the naming issue[edit]

I'm confused by the word "standard" when referring to time zones, UTC time offsets, and particularly the difference between daylight savings time and standard time.

My personal understand is that a time zone is a geographical area or region designated by civil authorities to have the same local time. For example, New York City is in the Eastern Time Zone and when it's 10:25 AM here, it's also 10:25 in Detroit, Atlanta, Miami, and Washington, D.C.

When we "spring forward" and "fall back" each year, don't we indicate the current time by expressions like Eastern Daylight Time and Eastern Standard Time? (Currently, both links simply redirect to Eastern Time Zone.)

The term standard does not refer to a zone but rathers serves to resolve any ambiguity over whether DST is currently in effect. And it also helps during that rare hour of the year when 1:30 AM occurs twice: in the fall, when daylight saving time ends, we have 1:30 AM (EDT) followed by turning the clocks back an hour (from 2am to 1am) and then we have 1:30 AM (EST).

Let's clean this up, okay?

According to Greenwich Time and the Longitude by Derek Howse (London: Philip Wilson, pp. 122–3) the first proposal for standard time was by Charles Ferdinand Dowd; his first proposal would have established time zones at 15° intervals from Washington, D.C., but his 1872 revision stated "The time of the 75th Meridian [West of Greenwich] is adopted as the standard time for all [rail]roads east of Ohio and the Allegheny Mountains..." We see that "standard" time referred to the concept of adopting one time for an area approximately 7.5° of longitude west and east of the central meridian. Daylight savings time came later. Also, not all states or portions of state use daylight savings time, so there are areas observing Mountain Standard Time in the middle of the summer. Jc3s5h (talk) 15:56, 13 May 2011 (UTC)
United States law explicitly uses the term "standard time" for both standard time and daylight saving time. The latter term is not used in US law. To wit: "the standard time of each zone ... shall be advanced one hour and such time as so advanced shall ... be the standard time of such zone during such period" (15USC260). It also does not use the term "standard time zone". Instead it refers the standard time of each zone, e.g. "The standard time of the first zone shall be known and designated as Atlantic Standard time" [for Puerto Rico and the U.S. Virgin Islands] (15USC263). — Joe Kress (talk) 19:34, 13 May 2011 (UTC)

National de facto official time / national media[edit]

As a non US resident I think this part of the article needs some editing! Looking at the webpages of CBS, SYFY, TNT... It seems that "de Facto" national media is using two time zones. It took me one hour to figure out what this "8/9c" stands for. It seems to be 8 o'clock EST / 9 o'clock CST, correct me If wrong. In my opinion this should be explained here, as well as why (sorry I still dont get it. Why is it not just 9c or 9cst or 8e or 8est??? The difference between EST and CST is always 1 hour, right? So why always stating the obvious?) greatings from overseas, marcus (talk) 13:26, 21 May 2012 (UTC)

Live events would not follow this pattern. A live event might be 8e/9c/10m/11p. Jc3s5h (talk) 14:36, 21 May 2012 (UTC)
Both prerecorded and live prime time programs from the three national broadcast (not cable) networks, ABC, CBS and NBC, are broadcast simultaneously (simulcast) in the Eastern Time and Central Time zones, during both Standard Time and Daylight Time portions of the year. Hence S for Standard and D for Daylight are not normally mentioned in program times. A program broadcast at 8 pm ET would be simulcast at 7 pm CT (not 9 pm). Mountain Time zone programs are broadcast one hour after the Eastern/Central simulcast, so this example program would broadcast at 7 pm MT. Pacific time zone programs are broadcast three hours after the Eastern/Central simulcast, for this example at 8 pm PT. I do not know the practice of cable networks. — Joe Kress (talk) 00:36, 22 May 2012 (UTC)
9/8c (or "Nine, eight central") is used in some places along the border of the Eastern and Central timezones. This is because the network itself broadcasts from within the Eastern timezone, but also broadcasts to areas in the central timezone as well. Because the network would serve viewers in both timezones, they need to clarify what time it begins for central viewers; otherwise they'd think it began at 9, only to see that they missed the show by an hour. - SudoGhost 00:49, 22 May 2012 (UTC)
This is for television schedules only. "9/8c" (spoken "nine, eight central") means the show is on at 9 on Pacific time and Eastern time broadcast feeds, and 8 on Central time broadcast feeds (i.e. two different times – 8CT/9ET and 12ET). Mountain time broadcast schedules seem to vary. Many cable systems provide more than one feed for a particular channel (e.g. TNT on the Eastern time schedule and TNTP on Pacific time), allowing more flexibility in watching/recording. The article should probably mention this (I'll look for a reference). For reference, 6 PT = 7 MT = 8 CT = 9 ET. —[AlanM1 (talk)]— 00:59, 22 May 2012 (UTC)

The title is self-contradictory. If this national time is de facto, then it's not official. — Preceding unsigned comment added by (talk) 17:05, 13 June 2012 (UTC)

English is not my native language but it seems to me that "de facto common time" or "de facto reference time" would be a better title that "official" (since the official time is oviously the 4 time zones). Or it could be changed entirely to "implicit use of Eastern Time" as my understanding of this paragraphs is that when a sentence is broadcasted nationaly and the time zone is not explicitly given, it is often the Eastern Time. (correct me if i am wrong, i don't live in the US) Jormund (talk) 11:08, 2 August 2012 (UTC)
Marcus' point is valid. This is unmistakeably happening and shouldn't be dismissed. All the time you see 8/7c on broadcasts. This confirms that default time is the Eastern Time.Dogru144 (talk) 15:41, 19 January 2014 (UTC)

Broadcast times used in the U.S. section[edit]

I changed this section to use a table, hopefully better showing the relationships between the local times and delays than the prose used previously.

Hawaii presented a problem that I solved as follows. The existing text claimed that Hawaii times were 2 hours before Pacific times. Currently, during Pacific Standard Time (i.e. winter in North America), the schedule for KITV shows only a 1-hour difference. I've therefore assumed that the delay from the Eastern time broadcast is fixed at 5 hours, and the local time therefore moves back during the summer (i.e. prime time is 6–9 in summer and 7–10 in winter). This needs clarification from a local, or when we can verify it during summer. —[AlanM1(talk)]— 00:43, 7 January 2013 (UTC)

I don't believe this table. It might be true for a live broadcast that is presented live in all time zones, maybe something like the Superbowl or the President's state of the union address. But the vast majority of programs are presented at the time of day that the broadcaster's consider appropriate for the type of show. For example, most dramas are presented in the evening.
The citations added in this edit don't do anything to verify the table, all those tables show is that different feeds exist. Jc3s5h (talk) 21:10, 22 February 2013 (UTC)
HI schedule shows 1 hour before PDT now. As far as accuracy, the offsets are just convention during prime-time. Naturally, local stations, or even the network feed, can be changed as needed, but prime-time lineups generally follow the stated offsets. —[AlanM1(talk)]— 11:51, 4 July 2013 (UTC)

Missing history section[edit]

The article and the related articles for specific time zones are missing discussion of how these zones have a history going back before 1966 and back to the late 1800s. Also, there is no discussion of how the border between the Eastern and the Central Time Zones has changed. At the start of the 20th century the boundary had Florida, Georgia and Ohio in the Central Time Zone.Dogru144 (talk) 15:36, 19 January 2014 (UTC)

Standard time isn't standard time in law[edit]

This edit added UTC offsets to every time zone. But the section is closely modelled on the cited US law. In the law, the phrase "standard time" does not mean the time when daylight saving time not in effect, it just means zone time as opposed to the actual observed time in each city. Thus, for the time zones that didn't have a UTC offset given, it changes depending on whether daylight saving time is in effect or not. So I undid the edit. Jc3s5h (talk) 14:49, 10 April 2015 (UTC)