Holidays in United States

Official national public holidays. Regional and religious observances may vary by area.

About Time in United States

Standard Time and the Day of Two Noons

Before the 1880s the United States had no unified system of timekeeping at all. Each city set its clocks by local solar noon, which meant the country had more than 300 slightly different local times. This made railroad scheduling nearly impossible, since a traveler crossing several states had to reset a pocket watch at almost every stop. The problem was solved not by government but by the railroad industry itself. Following a plan devised by William F. Allen, editor of the Travelers Official Railway Guide, American and Canadian railroads agreed to divide the continent into four time zones, Eastern, Central, Mountain and Pacific. At noon on November 18, 1883, station clocks across the country were reset simultaneously, and in some towns the clock struck noon twice within a few minutes, a moment newspapers nicknamed the Day of Two Noons.

For 35 years this railroad time had no legal standing, it worked simply because it was convenient. That changed on March 19, 1918, when Congress passed the Standard Time Act, sometimes called the Calder Act, which finally wrote the four zones into federal law and added a fifth zone for Alaska. The same act introduced daylight saving time as a wartime fuel saving measure, though DST itself was repealed the following year while standard time zones remained. Authority over the boundaries passed first to the Interstate Commerce Commission and, after 1966, to the Department of Transportation under the Uniform Time Act signed by President Lyndon B. Johnson.

The Master Clock of the United States Naval Observatory

Since the mid 19th century the United States Naval Observatory in Washington, D.C. has served as the nation's official keeper of time. In 1845, at the request of the Secretary of the Navy, the observatory mounted a time ball above its telescope dome so residents and ships on the Potomac River could set their instruments at noon. The observatory still operates a 12 inch telescope that is described as the longest continuously used government scientific instrument in the country, though its original astronomical timekeeping role has long since been replaced by electronic methods.

By the mid 20th century the observatory had installed its first atomic clock, and today it maintains an ensemble of roughly one hundred atomic clocks, collectively known as the Master Clock, inside a building covered in satellite antennas. Since 1967 the second itself has been defined by a fixed number of oscillations of the cesium 133 atom, precisely 9,192,631,770 cycles. This ensemble now anchors the timing signals broadcast by GPS satellites worldwide, with a backup Alternate Master Clock kept in close synchronization at Schriever Air Force Base in Colorado in case the Washington facility is ever disabled.

Selling the Exact Hour: Time Balls in American Ports

Long before radio signals, American cities relied on a simple visual device to distribute precise time: the time ball. Invented in 1829 by a British naval officer, a time ball was a large sphere hoisted up a mast and dropped at an exact moment so ship captains in harbor could calibrate their marine chronometers, instruments essential for calculating longitude at sea. The first American time ball began operating at the Naval Observatory in 1845. For decades the United States lagged behind European ports in adopting the technology, a fact contemporary writers complained about openly.

New York finally received its own time ball in September 1877, mounted atop a telegraph company headquarters near City Hall and triggered by a signal wired directly from the observatory in Washington. Because the country had not yet adopted standard time zones, the New York ball actually dropped a full twelve minutes before the one in the capital, reflecting the true difference in local solar time between the two cities. Time balls gradually disappeared after radio time signals became widespread in the 1920s, but their memory survives every December 31, when a lighted ball descends in Times Square, a direct descendant of this once essential piece of maritime commercial infrastructure.

The Clock at the Information Booth: Fact Behind a New York Legend

Set in motion in 1913 above the information booth in the main concourse of Grand Central Terminal in New York City, a four faced brass clock has served for more than a century as one of the city's most famous meeting points, simply known to generations of commuters as the clock. It was designed and built by a Brooklyn clockmaking firm, with the internal movement supplied by a Connecticut clock company, and each of its four faces measures about 24 inches across. The clock is kept synchronized with the atomic Master Clock in Washington, so it rarely drifts by more than a fraction of a second.

A persistent legend, repeated by tour guides and even briefly by an online encyclopedia in the 2000s, claims the four faces are carved from genuine opal gemstones and that auction houses have appraised them at ten to twenty million dollars. Historians who examined the terminal's original 1913 construction records and a 1980 landmark designation report found no such claim, the faces are actually made of opal glass, sometimes called milk glass, an inexpensive translucent material unrelated to the precious stone. The clock has had its share of real drama nonetheless, in 1968 one of its faces was struck and damaged by a police officer's stray bullet during a protest inside the terminal.

The Eleven Lost Days: America Adopts the Gregorian Calendar

Colonial America, as part of the British Empire, used the old Julian calendar until 1752, by which point it had drifted eleven days out of step with the solar year and with most of Catholic Europe, which had already switched to the Gregorian calendar back in 1582. Parliament's Calendar Act of 1750 corrected the error in two steps, it first moved the start of the legal new year from March 25 to January 1, then decreed that the day following September 2, 1752 would be called September 14, erasing eleven calendar dates entirely. Colonial newspapers, including one printed in South Carolina, published the act so residents would understand why nearly two weeks seemed to vanish from that September.

The shift is the reason George Washington is remembered as having two birthdays. Born on February 11, 1731 under the old Julian calendar, his birthdate shifted to February 22, 1732 once the eleven days and the new year date were both accounted for, and after 1752 he generally accepted February 22 as his birthday, though he was still noted attending a celebration on the old date decades later. Popular stories from England describe angry crowds rioting under the slogan give us back our eleven days, but most historians today regard this specific riot story as a later exaggeration rather than a documented event, since contemporary evidence for such a riot is thin.

Cleveland Abbe: The Scientist Who Argued for a National Clock

Cleveland Abbe was born in New York City on December 3, 1838, and trained first as an engineer before studying astronomy in Michigan and at an observatory near Saint Petersburg, Russia. Returning to the United States, he became director of the Cincinnati Observatory in 1868, where he built a volunteer telegraph network of weather observers and issued what is considered the first systematic public weather forecast in the country on September 1, 1869, earning him the popular nickname Old Probabilities.

In 1871 Abbe was appointed the first chief meteorologist of the newly formed national weather service, a position from which he championed the cause of standardized time long before it became law. He argued that a country reporting weather data from hundreds of stations on hundreds of different local clocks could never produce a coherent national forecast, and he was among the scientific voices supporting the four zone railroad system introduced in 1883. Abbe remained active in the weather service into his seventies and died in 1916, remembered today as a founding figure of the National Weather Service and an early advocate for the standardized time Americans now take for granted.

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