Why Don't We All Use the Same Time Zone?

By: Patrick J. Kiger & Austin Henderson  | 
clocks at different time zones
When it's 9:30 p.m. in London, it's 4:30 p.m. in New York. Who decided this? Adam Gault/Getty Images

Travelers often grapple with the pesky task of adjusting their watches or laptop clocks to match local time. Ever missed a conference call because you forgot the time difference between Chicago, Los Angeles and New York City? Time zones aim to sync our clocks with the sun's position, but they can be quite the headache when criss-crossing regions or coordinating with far-off contacts.

It's strange to think that time zones were invented as a way of reducing confusion rather than causing it. Since solar time varies as you move even a short distance from one spot to another across the planet, for most of human history, the time of day varied everywhere.


"Time was only measured by placement of the sun, so the sundial dictated what time it was," explains Steve Hanke, a professor of applied economics at Johns Hopkins University in Baltimore. Noon in London, for example, came 10 minutes earlier than noon in Bristol, 120 miles (193 kilometers) to the west. Even after people started using mechanical clocks in Europe in the 1300s, the inconsistencies persisted.

How Railways Standardized Time Zones

But confusion about the exact time wasn't a huge problem until the 1800s, when railroad trains started making it possible to quickly travel from one place to the next. All of a sudden, "people were missing trains, and you began to have near misses and train collisions occurring," Hanke says.

It wasn't just Europe plagued by a hodgepodge of time zones. "In the U.S., every city had a different time standard," Hanke adds. "You had 300 local time zones in the U.S., though the railroads eventually condensed it down into 100."


In 1876, a missed train due to a timetable error prompted Scottish-born engineer, Sir Sandford Fleming, to rethink global timekeeping. Fleming's innovative approach divided the world into 24 time zones, each roughly 15 degrees apart.

Rather than relying on local solar days, his system referenced the Royal Greenwich Observatory in the U.K., where Greenwich Mean Time (GMT) was set by the sun's position over the prime meridian. With most sea charts already marking Greenwich as the prime meridian (or longitude 0 degrees), it seamlessly became the dividing line between the Eastern and Western Hemispheres.

On Nov. 18, 1883 — which became known as "the day of two noons" — railroads in North America converted to a system of just four time zones: Eastern Time, Central Time, Mountain Time and Pacific Time.

Many cities passed ordinances adopting the system as well, and eventually, it became the standard across the U.S. Using GMT as the starting point forestalled any competition between different U.S. cities for the honor of being the prime meridian.


Can We Condense All These Zones?

But even with fewer time variations, time confusion again arose as a problem in the 20th century. The advent of air travel compressed distances even more, and the rise of the internet and mobile devices enabled instantaneous communication between people all over the planet and gave us a 24-7 culture in which we're tightly interconnected to events in distant places.

That's why a few years ago, Hanke and his colleague, Johns Hopkins University professor of physics and astronomy Richard Conn Henry, proposed an even simpler solution. They want to do away with time zones completely, and put the entire world on universal time (UTC). Under their system, when it's 9:00 in one place, it's 9:00 everywhere on the planet, even if it's morning in one place and evening in another.


In addition to making it easier to adjust to travel, having one time across the planet would make it easier for people who need to, say, set up conference calls with groups of individuals scattered from Montana to Germany, as Hanke, who is supervisory board chairman of a Dutch company, sometimes has to do.

"Endless confusion would be gone forever," Henry concurs in an email. "Life will be simpler!"

Since Hanke and Henry proposed abolishing time zones in 2012, others, such as bestselling author and New York Times essayist James Gleick, have supported the idea as well. And to a certain extent, a switch to universal time already has taken place.


UTC In Practice

Pilots and air traffic controllers in the U.S., for example, rely on universal time. Financial traders, whose dealings sometimes cross borders in addition to time zones, stamp transactions in universal time as well, to make sure that the pricing is correct. And the internet essentially runs on universal time.

Some might wonder if a switch to universal time would alter the rhythm of people's daily schedules, but Hanke doesn't think so.


"People say, 'Oh, if we went universal time, that would mean we'd have to be opening businesses when it's dark outside.' No, your business would go like it does now, with the sun. In New York or Baltimore, if you open normally at 9 a.m., that would be 14:00 [2 p.m.] on your watch," he says (assuming GMT is 9 a.m.)

It might take some getting used to, but Hanke thinks that in a generation, children who grew up with UTC would no longer associate, say 7 a.m. with breakfast time or 9 a.m. with starting work. And the switch not unheard of.

"China currently has this 'problem' in that it has one time zone for a huge swath of East-West real estate," Henry adds. "But it is totally cured by having local decisions as to opening/closing times for businesses and so on. That would obviously be essential for a worldwide system."

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.


Frequently Answered Questions

How many time zones are there in the USA?
The six time zones in the USA are: Eastern Time Zone, Central Time Zone, Mountain Time Zone, Pacific Time Zone, Alaska Time Zone and Hawaii-Aleutian Time Zone.
Why do we have to remember daylight saving time, and which areas observe it?
Daylight saving time was introduced to make better use of daylight and save energy. Most of the USA observes daylight saving time, except for Arizona (with an exception for the Navajo Nation) and Hawaii.
When does daylight saving time begin and end?
Daylight saving time begins on the second Sunday in March and ends on the first Sunday in November.
Why were time zones introduced in the first place?
Time zones were introduced to coordinate train schedules and reduce confusion caused by local time variations, especially with the rise of the railroads.
Who determines the time zone boundaries?
A combination of federal law, interstate commerce considerations and geography determine time zone boundaries.
Is it true that certain places in the USA don't follow daylight saving time?
Yes! For example, Arizona (except the Navajo Nation) and Hawaii do not observe daylight saving time.