How Long Is A Decade In Years?

A decade is a period of time equivalent to 10 years. The word “decade” originally stems from the Greek word dekas (δεκάς), meaning “a group of ten.”

This word was transmitted through the Romans, who commonly used the prefix dec- to describe collections of 10 items, such as a decathlon, a collection of 10 athletic challenges, or a decagon, a regular 10-sided polygon. Other divisions of time that derive from Latin include the century (100 years) and the millennium (1000 years).

Technically, any group of 10 years is its own decade. The term “decade” is generally used to refer to periods of time based on the tens digit of the calendar year. So the “1980s” refers to the decade of time between 1980–1989.

Since the Gregorian calendar begins on 1 AD (there is no year 0 in the Gregorian calendar), the first decade of the Gregorian calendar refers to the period of time between 1–10 AD, the second decade refers to 11–20 AD, etc. So, even though “the nineties” refers to the years between 1990-1999 AD, the 200th decade refers to the time between 1991–2000 AD.

An event that recurs every decade is called decennial. Similarly, an event that recurs every 100 years is a centennial event and every 1000 years is a millennial event. For example, the U.S. government administers a census decennially; every 10 years. Many high school and college reunions occur every 10 years as well.

Decades have come to culturally symbolize a kind of rebirth; a clean slate from which people can start again. The identification of a decade as a distinct period of time that divides our experience has given the concept of “decade” a lot of symbolic meaning. Decades throughout U.S. history are often referred to by a nickname that encapsulates major cultural events or symbolizes the general cultural ethos during that time. For example, “the Roaring Twenties” refers to the 1920s, a time of great economic growth and sociocultural change. The 1940s are sometimes referred to as “The Fighting Forties” as a reference to the United States’ involvement in both the European and Pacific theatres of WWII. In some ways, the decade is the historical unit of time; history is often divided into events that occurred in their respective decades.

Important Events Of 20th Century By Decade

The 1900s

  • 1903 – The first manned flight by the Orville brothers.
  • 1905 – Albert Einstien publishes his paper On the Electrodynamics of Moving Bodies, introducing the Special Theory of Relativity.
  • 1906 – The 1906 earthquake of San Francisco kills 3000 people.
  • 1907 – Guglielmo Marconi establishes the first trans-Atlantic radio communications system.
  • 1908 – The Tunguska event occurs. An explosion in Siberia decimates 770 square miles of surrounding forest. The explosion is generally attributed to a meteor impact.

The 1910s

  • 1910 – The Mexican Revolution begins.
  • 1913 – Niels Bohr introduces his semiclassical model of the atom, laying the foundation for future quantum mechanics.
  • 1914 – Gavrilo Princip assassinates the Austrian Archduke Franz Ferdinand in his motorcade in broad daylight, igniting the European powder keg and setting off WWI.
  • 1916 – The first manned tanks are used in war by the French during the Battle of Fleur-Courcelette.
  • 1917 – The U.S. officially enters WWI. The October Revolution in Russia deposes the Tsarist autocracy.
  • 1919 – The Treaty of Versailles is signed, officially ending WWI. Ernst Rutherford discovers the proton.

The 1920s

  • 1920 – The Mexican Revolution ends. Prohibition-era in the U.S. begins. Gandhi begins his movement in colonial India.
  • 1921 –  Adolf Hitler becomes Fuhrer of the Nazi party. The Soviet Union annexes the territory of Georgia.
  • 1923 – TIME magazine is first published. The Great Kantō earthquake in Japan kills 105,000 people.
  • 1924 – The Islamic caliphate is abolished, officially dissolving the Ottoman Empire, the single longest-lived empire in human history.
  • 1928 – Alexander Fleming discovers penicillin, ushering in a new age of antibiotics. Walt Disney creates Mickey Mouse.
  • 1929 – Wall Street crashes on Black Tuesday (October 29, 1929) and the Great Depression begins. International trade drops by 50% during this time.

The 1930s

  • 1930 – First FIFA world cup is hosted in Uruguay. Pluto is discovered by Clyde Tombaugh.
  • 1931 – Mao Zedong establishes the Chinese Soviet Republic.
  • 1932 – The neutron is discovered by British physicist James Chadwick. BBC begins broadcasting.
  • 1933 – Prohibition-era in the U.S. ends.
  • 1934 – Hitler declares himself Fuhrer of Germany. The infamous American mobster John Dillinger is killed by the FBI.
  • 1936 – The Spanish Civil War begins. The last Tasmanian Tiger, named “Benjamin,” dies in Hobart.
  • 1937 – The first artificial element Technetium is synthesized.  The Hindenberg zeppelin crashes in Lakehurst, New Jersey.
  • 1938 – The Great Purge in the Soviet Union kill 700,000. Superman makes his first appearance in Action Comics #1.
  • 1939 – The German invasion of Poland begins WWII.

The 1940s

  • 1940 – Germany invades France.
  • 1941 – Japan attacks Pearl Harbor. Operation Reinhard commences and the Nazis begin exterminating Jews.
  • 1944 – The Allied Forces storm the beaches of Normandy on D-Day (June 6th). The first electronic computer Colossus is created.
  • 1945 – WWII ends. President Truman drops 2 atomic warheads codenamed “Fatman” and “Little Boy” on Nagasaki and Hiroshima. The U.N. is founded.
  • 1946 – The first images of Earth are taken from space. The Philippines gains independence from the U.S.
  • 1947 – American pilot Chuck Yeager becomes the first human to break the sound barrier.
  • 1948 – The U.N. annexes territories in Palestine, creating the modern nation of Israel. Gandhi is assassinated.
  • 1949 – Mao Zedong establishes the People’s Republic of China.

The 1950s

  • 1950 – The Korean War begins.
  • 1952 – Egypt gains independence from Great Britain. Jonas Salk invents the Polio vaccine.
  • 1953 – Francis Crick and James Watson discover the double-helical structure of DNA. Elvis Presley begins his musical career.
  • 1954 – The U.S. Supreme Court decision in Brown v. Board of Education abolishes racial segregation in public schools. The Soviet Union becomes the first to generate electricity via nuclear power.
  • 1957 – The soviet union launches Sputnik I.
  • 1958 – NASA is founded. The first cassette tapes are invented.
  • 1959 – The Vietnam War begins. Human population reaches 3 billion.

The 1960s

  • 1960 – The first birth control pill becomes commercially available. The first laser is built.
  • 1961 – Russian cosmonaut Yuri Gagarin becomes the first human in space. The Berlin Wall is constructed.
  • 1962 – The Cuban missile crisis occurs.
  • 1963 – Martin Luther King Jr. gives his famous “I have a dream” speech during the March on Washington. JFK is assassinated by Lee Harvey Oswald.
  • 1964 – The Civil Rights Act in the U.S. abolishes segregation.
  • 1967 – The Beatles release the album Sgt. Pepper’s Lonely Hearts Club Band.
  • 1968 – MLK is assassinated by James Earl Ray.
  • 1969 – American astronaut Neil Armstrong becomes the first human on the moon. Charles Manson and his cult commit the Manson family murders.

The 1970s

  • 1970 – 4 students are killed by the Ohio National Guard during the Kent State Massacre. The Treaty on the Non-Proliferation of Nuclear Weapons is ratified.
  • 1971 – The first microchip is invented.
  • 1974 – Richard Nixon resigns as U.S. president after the Watergate scandal. the carnation Revolution establishes a democratic government in Portugal.
  • 1975 – The Vietnam War ends with the Fall of Saigon. The Khmer Rouge in Cambodia takes power and begins executing political opponents.
  • 1976 – Steve Wozniak and Steve Jobs found the computer company Apple.
  • 1979 – Smallpox is considered eradicated. The Sandinistas in Nicaragua overthrow the Somoza dictatorship.

The 1980s

  • 1980 – Mt. St. Helen’s erupts in Washington state. Archbishop Oscar Romero is assassinated in El Salvador by right-wing extremists.
  • 1983 – The first GPS becomes commercially available. The U.S. invades Grenada.
  • 1984 – the HIV virus is identified as the cause of AIDS.
  • 1986 – The Challenge shuttle disaster occurs. The Chernobyl reactor has a nuclear meltdown.
  • 1989 – The Fall of the Berlin Wall and the dissolution of the Soviet Union. The Exxon Valdez oil spill occurs.

The 1990s

  • 1990 – Tim Berners-Lee invents the World Wide Web. The Hubble Space Telescope is launched.
  • 1992 – The EU is created through the Maastricht Treaty. The first extrasolar planets are discovered.
  • 1994 – Nelson Mandela is elected in South Africa. Kim Jong-Il becomes the leader of North Korea.
  • 1995 – Domestic terrorist Timothy McVeigh commits the Oklahoma City bombings, killing 168 people. The Bosnian war ends.
  • 1997 – Tony Blair becomes prime minister of the U.K. Princess Diana dies in a car crash in Paris.
  • 1998 – Larry Page and Sergey Brin found the company Google.
  • 1999 – The EU adopts the Euro as its official currency. Hugo Chavez becomes president of Venezuela. Dylan Klebold and Eric Harris commit the Columbine High Schol Massacre. The total human population reaches 6 billion.

Other Names For Units Of Calendar Time

A decade is just a name for one particular span of time on a calendar (10 years). Other names for spans of calendar time include:

  • nundine – 9 days. Used by the Romans to set their market calendars.
  • fortnight – 2 weeks (14 days)
  • quinzième – 15 days. Derives from the French word for 15, quinze.
  • dog year – about 1/7 a year (~52 days). Named after the life expectancy of the average dog.
  • biennium – 2 years.
  • triennium – 3 years
  • quadrennium – 4 years. Mostly used to refer to the period of time in between each Olympic games.
  • lustrum – 5 years. Every lustrum, the Romans would have an empire-wide census.
  • score – 20 years. Commonly associated with opening words of Abraham Lincoln’s Gettysburg Address: (Four score and seven years ago….)
  • quinquagenary – 50 years. A person who is 50+ years old is called a quinquagenarian.
  • century – 100 years. A person who is 100+ years is called a centenarian.
  • bicentennium – 200 years.
  • millennium – 1000 years. The plural of “millennium” is “millennia”
  • Piktun – 7885 years. 1 Piktun corresponds to one full cycle of the Mayan Long Count calendar.
  • megaannum – 1 million years.
  • galactic year – approximately 230 million years. A galactic year is the amount of time it takes the solar system to rotate around the Milky Way Galaxy once.
  • Kalpa – 4.32 billion years. In Buddhist and Hindu cosmology, 1 Kalpa is the amount of time between the creation and recreation of the universe.

About The Author

Alex Bolano

When Alex isn't nerdily stalking the internet for science news, he enjoys tabletop RPGs and making really obscure TV references. Alex has a Masters's degree from the University of Missouri-St. Louis.

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