History of 2010: Start of a New Decade?

2010 NumbersHISTORY OF 2010: A NEW DECADE?

As the chronometer clicks over from 2009 to 2010, many are heralding the end of one decade and the beginning of another, regaling the best and worst at the end of the first decade of the 21st century.

Except that it isn’t.

Clicking over to 2010 does mark the end of a decade, indeed any year is the end of a 10 year period preceding it, and it is certainly the beginning of “the decade of 2010s” as any year is the start of a 10 year period following it. And of course, it’s the end of the “aughts,” the ’00s. While this term is not used as commonly as at the beginning of the 1900s, we’re coming to the end of “Aught 9.”

But it is not the ending of THE decade, at least not the end of the first decade of the 21st century. Why is that?

In the same way that the year 2000 was not the beginning of the 21st century, 2010 is not the beginning of the second decade of the 21st century. I know what you’re thinking:

“But wait, didn’t every major capital city in the world have celebrations on December 31, 1999 to usher in the year 2000? Wasn’t the Eiffel Tower lit up like a Roman candle… or at least a French candle?”

2001: a space odysseyTrue enough, but the calendar did not start with the Year 0, and so 2000 was not the beginning of the 21st century. That’s why Arthur C. Clarke entitled his science-fiction epic 2001: a space odyssey. He wanted to mark the beginning of the Third Millennium, the correct start of the 21st century. You’re probably protesting:

Then why did we make such a big deal out of the Year 2000?”

And well you might ask. Have you ever watched your odometer click over from 1999 to 2000? But that’s only part of the answer. At least equally powerful a motivation was that the year 2000 was the end of the Y2K scare, when we expected that a computer time coding issue would cause the end of civilization as we know it.


Officially, according to the current dating system — which has been in use for simply ages — dates started with Year 1 or AD 1, Anno Domini, (in the year of our Lord) which immediately followed 1 BC, or Before Christ. There was no Year 0. The fact that Jesus was born neither in Year 0 nor Year 1 but at least 4 years earlier we’ve discussed previously. By now you’re probably thinking:

“Didn’t it seem odd to people at the time that one year it’s 1 BC, and the next year it’s AD 1?”

You would think so, except of course, they weren’t using the current Gregorian Calendar that we now use, rather the Julian Calendar, named after that famous Roman Julius Caesar who subsequently got a month named after him. The Romans counted from the “founding of the City (of Rome),” ab urbe condita or A.U.C, about 753 BC. So AD 1 would have been 754 A.U.C. (Although, just between you and I, the Romans preferred marking their calendars by what year it was under the reign of the current consul in government.)

Still with me?

2010So, when New Year’s Day comes in 2010 it won’t be the beginning of the second decade of the 21st century. Instead, that will start in 2011.

In any event, what will you start saying:

“Two thousand ten” or Twenty-ten”?

Bill Petro, your friendly neighborhood historian

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About billpetro

Bill Petro writes articles on history, technology, pop culture, and travel. He has been a technology sales enablement executive with extensive experience in Cloud Computing, Automation, Data Center, Information Storage, Big Data/Analytics, Mobile, and Social technologies.


  1. Garry Holman on December 28, 2009 at 9:09 pm

    Right you are, Bill, at least technically. The “second decade of the 21st century” does indeed not start until 2011. Of course, this game we play every century leads to some poor misbegotten souls like the guy I read about who tried to argue that the last year of “The Seventies” was really 1980. As a Baby Boomer, the thing I consider much more significant about the year 2010 is that on this coming January 1, the year 1960 (“The Sixties,” for God’s sake) becomes “50 years ago.” Geez, now I really feel old.

    • Bill Petro on December 28, 2009 at 9:12 pm

      The ’60s were 50 years ago? How did that happen? I guess I wasn’t paying attention. You’ve heard it said that “if you remember the ’60s then you weren’t there,” but I’ve heard Steve Jobs say “the ’60s happened during the ’70s.”

  2. Stuart Miniman on December 29, 2009 at 9:32 am

    Nice post Bill. How about ‘010 (with credit to Stephen Colbert) – we can get another 90 years out of the ‘0xx nomenclature 🙂

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  5. KD on December 30, 2009 at 12:06 pm

    Good post. As much as your history of the calendar is correct, I’d offer that one thing is missing. The reason for no year 0 (zero) is that the Roman numerals did not have a representation for zero. The European system didn’t start its use of the Arabic numbering system until about 900AD. The concept for 0 (zero) still took about another 100 years. There is only minimal discovery of potential use of ‘nulla’ in history before this.

    Based on the numbering system used by modern society, and simple math, the number has changed in the ‘tens’ position, indicating a new set. Basically, the beginning of our calendar never had a full 10 grouping of ‘aughts’, just 9 years. We have had perfect decades every since of the patterned year groups.

    Your argument of the millennium is valid as to a count of 1000 years since the beginning of the defined calendar system, no argument there. However, by accepted use of the terms 50’s, 60’s, etc…, the end of the ‘aughts’ have been reached. We start a new decade, even if that is not a millennia plus 10. A decade is not defined on where the calendar starts, but in reference to the grouping of 10 years. A person can be a decade old no matter what year they were born in, as long as 10 years has passed from that point. So the decade of the 70’s is expressed from 70 – 79. As such the year of the ‘aughts’ will be done. It may not be the end of the first decade of the millennia, but it is the end of a defined decade.

    Just offering an opinion. 🙂

    • Bill Petro on December 30, 2009 at 12:20 pm


      Thanks for the helpful comment. I neglected to discuss the “History of Zero,” perhaps a future article? My friend Jim Herriot commented that there’s a book on this subject called “Zero: The Biography of a Dangerous Idea” by Charles Seife.

      It makes one wonder: is this a book about nothing?

      I think we’re in agreement about “decade.” I hope that I conveyed that we’re at the end of “a decade” but not the end of “THE decade” (first of the 21st century).

      I threw in the “aughts” just for a bit of historical emblandishment, perhaps this added confusion. I’ve rarely heard aught used since the 1900s. Professor Harold Hill in “The Music Man” claimed he graduated from the “Gary Conservatory, Gold-Medal Class of Aught 5.”

      • KD on January 4, 2010 at 11:31 am

        🙂 Love the book comment.

        I believe we are in agreement. I guess I was trying to point out the grouping of the decades versus a decade relative to the beginning of the calendar system. That is, that the 70’s would be considered the decade that started on January 1, 1970 and ended on December 31, 1979.

        By century and millennia reference, we are now in the last year of the 201st decade of the modern calendar system.

        Happy New Year!

  6. Susie Neer on January 1, 2010 at 10:15 am

    Thank you for the post, me and my husbund was arguring about it, he was telling me the last night was the last day of the decate and I completly desagree about it!!!

  7. Grant on January 1, 2010 at 3:30 pm

    Strictly speaking, the calendar didn’t start with a year 1 either. The current dating system didn’t catch on until Christianity had become dominant in the Roman empire, around the fifth century.

    • Bill Petro on January 1, 2010 at 3:48 pm


      It all depends on what calendar you’re talking about 🙂 I’ve discussed each across all of my linked articles.

      Secondly, Christianity became dominant in the Roman Empire by the middle of the 4th century. Its rise, at least numerically, began with it being made a legal religion under Constantine following 313, and was the majority by the middle of the century, even before Emperor Theodosius make it the official state religion in before the end of the 4th century.

      See: http://bit.ly/5YQLEM

  8. M Frost on January 1, 2010 at 5:07 pm

    This isn’t hard to work out people…you have to forget about age, which is what most people use to get the year wrong; when you became 10 it was after existing for 10 years right? Yes, but the calendar is completely the opposite in how it reckons time – imagine if time started on the day you were born; you’d be 1 day old on 1/1/01 but you would be in calendar year one already. 365 days later on your birthday you would be aged one but the date would be 1/1/02. This is because, in effect, in our 10th year we are regarded as 9 and so many days while the calendar, in its 10th year, is called 10 from the 1st day of its 9-years-and-something-days. You would be 10 on 1/1/11 but only 9 on 1/1/10, quite plainly NOT the first year of a new decade but the last. Its just that the year turns 10 on the 1st day of its 10th year while people turn 10 on the last day of their 10th year (actually the day before your birthday of course, which would be the 366th day). In the same way that “20th century” for dates in the 1900s confuses stupid people, a year ending in 10 covers the period 9 years and 1 day to 9 years and 365 days of the decade

    • Bill Petro on January 1, 2010 at 5:14 pm

      M Frost,

      Excellent comment. You’re right, post people use the analogy of their birthday, and get confused.

  9. JR on January 2, 2010 at 8:29 am


    M Frosts comments were very clear and his example of birth on 1/1/01 will make the span of time on 1/1/10 9 years ad not 10 until 1/1/11. But, wouldn’t birth on 1/1/00 make one 10 on 1/1/10 and starting the next 10 years from that time? Am I not undrstanding the history of zeros?
    Sorry to drag this out but I’m better with crayons than numbers.

  10. Bill Petro on January 2, 2010 at 10:23 am


    Yes, that’s part of the problem. When you’re born, you’re 0 years old. But the calendar did not start that way — there was no Year 0, in part because the Romans didn’t have it yet. It was neither part of the earlier Julian Calendar, nor the later Gregorian Calendar that we use now.

  11. Jeff on January 3, 2010 at 12:47 am

    This is the 21st century even though the year starts with 20xx. That is because we refer to the date by the year or century we are in and not by the actual number of years that have passed. This would be too confusing and yet leads to the present confusion. Can you imagine saying this is 2009 and two days, and three days, and four days….. and so on …

    • Bill Petro on January 3, 2010 at 12:52 am

      Thanks Jeff. I’m not sure: are you agreeing or disagreeing with the article?

  12. M Frost on January 4, 2010 at 8:10 pm

    OK, I’ll try again in even simpler terms to point out where you ‘Year Zeroes’ are going wrong. If you are age 9 you can say this in two ways: “I am 9 years of age” or “I am in my 10th year”. Both are correct. This millenium is 9 years old or is in its 10th year. Both these are correct. We just usually use past tense to describe our age (9) and present tense to describe the year (10th)

    From the very first second of time the first year has begun; you are in the 1st year. You cannot possibly be in year zero as zero implies an absence of anything yet at least a second has already passed and been counted, counted as part of year one.

    The first day of the first month of the first year would be 1/1/01. If you argue that it should be 1/1/00 because a year hasnt passed then you must also argue that the 1st day must be day zero as a full day hasnt passed and month 1 must be month zero because a full month hasnt passed. In other words, the first second in time must have been on day 0/0/00. Using your logic of allowing a zero for uncompleted wholes, today wouldnt be January as January is not yet complete. It wouldnt be January until 1st February but of course it wouldnt be the 1st until the 2nd so the 1st February becomes the noughth of January. Todays date (5th January 2010) would be 4th December 2010 (because New Years Day would have been on the nougth of December). This is the only way to make 2010 a zero year at the begining of a decade rather than a 10th year at the end of a decade

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