I got a question. 21 years is 7,670 days so if the dates were 7,670 days apart, example March 1, 1991 and February 29, 2012 or February 28, 1991 and February 28, 2012 and the person was allowed to walk into a bar born on February 28 and February 29 wasn’t there in 1991, shouldn’t you be allowed as well? The only reason why you would’ve been born on March 1 was because February 29 was skipped.
BTW, I was born on July 7, 1991 and I’m 22 years old today.
WAG but I’m pretty certain that you are not 21 years old until you have lived past 21 birthdays. The actual number of days has nothing to do with it.
The day you were born on and 21 years later, you are 21 for legal purposes, there is NO allowance for leap year in any state’s “computation of time” for alchoholic purchases.
And happy birthday. Tomorrow.
What if you were born on February 29? If February 29 came this year, it wouldn’t be coming in 21 years. Also why does it seem that if you’re born in certain years before the end of the century before a leap year and then a leap year is skipped and the same date is 7,669 days apart, you can purchase alcohol the day before your 21st birthday if the two dates aren’t even 21 years apart, because I know what this is? A leap year has to be skipped in order to make a correction to the calendar.
Or how about this? In future years, I change the leap years from every 4 years to every 5 years and insert the double leap year every 30 years. Now I’m no longer talking about legally 21 but about being able to obtain a driver’s license. In the 15 year period, there are 5,478 days and the 16th year because it’s the 30th year has 367 days. 5,478 days + 367 days = 5,845 days and 16 years is fewer than 5,844 days. Assuming my calendar may be accurate that if you’re born on March 1, 99929 and 16 years later, it’s February 29, 99945, 5844 days later, could you get a driver’s license that day? Remember what I said about the skipping of a leap year.
And it’s my birthday today in the US. The sunrise was the exact same as my commerative sunrise for that day in that year. And today is an exact match of July 7, 1859, precisely 154 years ago and that day was on Thursday.
Yeah, I think it’s time someone actually takes a look at the birth hours and counts 5 hours and 48 minutes from that each time. That’ll determine the day for a birthday if at that! 
Some localities have instituted (or proposed) a day after system to prevent people from getting blitzed after midnight passes on the day before their birthday. It’s pointless as far as I can tell, they’ll just be back the next night and drink even more.
And what’s the point of counting another year at the same date and time you were born? The year or years (plural) isn’t a full number of days. Just take a look at 4 years. It’s about 1,460.96 days. If the year wasn’t NOT a full number of days, we wouldn’t need leap years and then we wouldn’t have this problem. If the days were about a minute longer so that we’d only have 365 days in a year and not 365.24 or 365.25 days, we wouldn’t have this problem either.
Also it leads me to believe that in the far future that because the Declaration of Independence was signed on July 4, 1776 and that was before the calendar had a correction into July 5 in the year 1800 and then beyond that up until 1803 before the first leap year again, when we stop having the needs for leap years, Independence Day should be moved permanently to July 5. It was on the same day of the year this year because the date of the Summer Solstice was the same as 237 years ago, but not the same as 87 years ago. My grandma was born on the 5th and I believe she turned 87 on the 4th. 87 years was more than 31,776 days at the Summer Solstice, but I believe it was fewer than 31,776 days just a few days ago, checking at sunrise times and the length of days.
MichaelXD, are you aware that the solar system doesn’t operate in a fashion that allows easy mathematical calculations of “days,” “hours,” and “years”? We humans are trying to impose those measurements upon a system that is not organized that way. Something has to give. Leap years are one of those factors that allow the give.
You might enjoy reading Questioning the Millennium, by Stephen Jay Gould. Although 2000 has come and gone (those were the days!), this book is still useful and will go far to answer your questions.
Could you explain this, please? I also was born July 7th as it happens. According to your OP, you posted at 12:44pm, today, July 6th in the Eastern Time Zone of the U.S. (I believe the settings I have for the Dope automatically translate each post to my local time). I guess somewhere to the east of me (Europe? Asia?) it is July 7th, but not in the U.S.
What do you mean by “commerative” sunrise?(I assume you mean commemorative, but you may just be using a different term I am not familiar with)
And on what basis is today an “exact match” of any other day in history (particularly confusing since today is a Saturday and you state that exact match day was a Thursday). What matches?
Please note, I am not trying to be argumentative or snarky, I am genuinely curious as to the basis of your statements.
The length of day. The weekday is irrelevant. There is no right or wrong weekday. It’s the weekdays that elapsed which causes it to be Saturday. July 7, 1859 was 14 hours 44 minutes and 59 seconds and today is 14 hours 44 minutes and 59 seconds. The length of day from sunrise to sunset is precisely the same. The length of day and year fluctuate so it won’t be the exact same length as July 8, 1859 tomorrow nor was it the same exact length as July 6, 1859 yesterday. I found this on timeanddate.com. You should use it.
Commerative means first. When I saw my first sunrise, it was July 7, 1991.
If one desires this level of precision to determine when they are 21 just so they can legally drink, said precision is the least of their worries. One should expand the level of precision to where you never become a Darwin Award nominee.
I’ve had a similar (academic, don’t need answer fast) question about “Romeo and Juliet” laws. Yesterday, Sam was 21 and Robin was 17. Today, Sam is 22 and Robin is 17. Tomorrow, Sam will obviously still be 22 and Robin will be 18. Was the relationship legal yesterday (assuming AOC is 18 and R&J is four years)? What about today?
It seems to me unjust that it should vacillate between legal and illegal, and more just (or at least unjust in a way outside the scope of this discussion) that it should be illegal until tomorrow – Sam’s 4th birthday was past when Robin was born, that’s more than a four-year difference. But when they met, and asked each other’s ages, they seemed to each other to be four years apart.
Pretty sure a judge would get involved in that particular case.
As for the original question, I’m certain the local laws define it in some way.
Since the question is only important to a few people, and only for a short time, it’s not going to change.
Driver’s license law isn’t going to change either- know why? Kids can’t vote!
ETA-
[citation needed]
From my Random House dictionary:
commemorate verb:
Nothing about it being the first anniversary. Or even an anniversary at all.
There’s at least three different types of years that I know of, they’re very close but still not the same and none of them line up precisely with days. Thus, it doesn’t make sense to try to legally define a period of 21 years by calculating the number of days it supposedly is. And if we were to do that, why stop the precision at just days and not go even farther. Someone born in the early hours of the day is theoretically 21 sooner than someone who was born late in the evening. What if a pair of twins are born straddling midnight, so one is born just a few minutes before and the other a few minutes after. It seems odd that two twins would have different birthdays and one might be legally allowed to drink before the other.
Besides, do you really want people selling alcohol, cigarettes or other age restricted products or services trying to take into account the complex relationships between the various revolutions and orbits and human-devised calendars just so someone may have a drink or a smoke a little sooner or later? Legally, it just makes sense to simplify it and getting it right generally to within a day or so seems pretty reasonable.
And, really, for me, I guess I was doubly screwed because my 21st birthday was on a Sunday and sale of alcohol was illegal on Sundays there, so I had to wait essentially two days to have my first legal drink. Oh the horror!
Seeing as how its well established that someone becomes responsible enough to drink alcohol EXACTLY 21 YEARS after they poked their little head into the world and not a day or an hour or a minute sooner, I’d say we need to answer this question definitively as soon as possible. Otherwise, because of leap years and divergent sun rises we run the risk of allowing someone to drink before they are really ready. Or worse, denying those sweet, sweet intoxicants to someone otherwise rightfully entitled due to the capriciousness of our planet’s wobbly orbit. Stoopid planet!
Or not.
What happens if you feed the OP after midnight?