As we get ready to change our clocks this Sunday, you might hear a lot of people railing against daylight saving time. But do they even know what they're talking about?
Daylight saving time in the United States is actually pretty complex. Sure, we all know that we "spring forward" and "fall back" with the seasons. But whether these changes actually end up making daylight hours coincide more closely with the hours that you're awake varies considerably depending on where you are in the United States.
Andy Woodruff, a cartographer, has made this amazing series of maps that shows how little most people understand about daylight saving time, but also, at the same time, clearly explains it. Personally, I discovered that I don't hate our current system as much as I thought I did. Maybe you will, too.
But let's go back for a second.
Why does the effect of daylight saving time vary so much across the United States? It's because the effect is determined by two separate things. First, there's your total daylight hours, which are just a function of your latitude. And then there's how those daylight hours correspond to the clock, which depends on your longitude.
The connection between latitude and total daylight hours is pretty straightforward. In his post, Woodruff illustrates that by way of this chart below, which appears on Wikipedia Commons. The chart is not as complicated as it first appears. New York City, D.C., Chicago and San Francisco are all within a few degrees of 40 N. So you can follow the dark blue line across to see how many hours of sunlight you have in a typical day -- eight in the depths of winter, growing to 14 at the height of the summer.
As you move closer to the equator, there is a lot less seasonal variation in sunlight -- you're pretty much getting 12 or 14 hours all year-round. At the poles, of course, there's a huge variation, with no sunlight in the winter and 24 hours of sunlight in the summer.
Longitude is a little trickier. There's your time zone, of course, but there's a lot of variation within that. The farther east you are in your time zone, the earlier the sun will rise and set. In eastern Maine, the sun rises almost an hour earlier than it does in Michigan, even though they're both on Eastern Time.
Woodruff's maps put all these variables together, showing how many days of the year have reasonable sunrise and sunset times across the United States. In these maps, he defines "reasonable" sunrise and sunset times as 7 a.m. and 6 p.m. The maps are interactive, so you can visit his site and play around with those numbers if you want.
Here are how many days have sunrises before 7 a.m. if we keep our current system. On Woodruff's maps, a dark purple color means there are fewer days with sunrise before 7 a.m., while the yellow color indicates more days. As you can see, the answer varies a lot across the country, from only 36 days in western Texas to nearly the entire year in the Florida panhandle.
Here's what that map looks like if we abolish daylight saving time year-round. Notice Americans in lots of different places would get a lot more sunlight in the morning.
And here's what the same map would look like if we decide to use daylight saving time -- what we're starting on Sunday -- year- round. Using daylight saving time year-round would result in some darker mornings for early risers. In the western edges of several time zones, the sun would be rising after 7 a.m. on most days of the year.
That may be enough to convince some of you that daylight saving time is a pretty bad invention. But before you decide that, let's look at the sunsets.
Here's what the sunset map looks like if we keep the current status quo of using daylight saving time in the summer but abandoning it in the winter. With the current system, all parts of the country have between 200 and 300 days where the sun sets after 6 p.m. Not too bad.
If you look closely, you can see something interesting in this map -- and the first map above. Arizona doesn't follow daylight saving time (neither do Hawaii and some U.S. territories), which is why it's colored differently. The Navajo Nation in Arizona does, and the Hopi Nation, which is surrounded by the Navajo Nation, does not -- which is why you see a small darker orange square in Arizona.
If we abolish daylight saving time, sticking with the system we use in the winter year-round, things look a little darker. Now some parts of the country that are at the eastern edge of their time zone only see 150 or 160 days a year with sunsets after 6 p.m. To me, that seems pretty sad, but you might feel differently if you're an early riser.
One more option. Here's what the map looks like if we use daylight saving time -- the system we use in the summer -- year-round. Almost all parts of the country have at least 230 days where the sun sets after 6 p.m., while many parts have 365. For most of us, that means fewer days leaving work in the dark.
Here's a poster by Woodruff that summarizes these findings.
So which one do you really prefer? Tell us in this poll:
You might also like: