The 20th century began on 1 January 1901 (MCMI), and ended on 31 December 2000 (MM). It was the last century of the 2nd millennium and was marked by new models of scientific understanding, unprecedented scopes of warfare, new modes of communication that would operate at nearly instant speeds, and new forms of art and entertainment.
The century saw a major shift in the way that many people lived, with changes in politics, ideology, economics, society, culture, science, technology, and medicine. The 20th century may have seen more technological and scientific progress than all the other centuries combined since the dawn of civilization. Terms like nationalism, globalism, environmentalism, ideology, world war, genocide, and nuclear war entered common usage. Scientific discoveries, such as the theory of relativity and quantum physics, profoundly changed the foundational models of physical science, forcing scientists to realize that the universe was more complex than previously believed, and dashing the hopes (or fears) at the end of the 19th century that the last few details of scientific knowledge were about to be filled in. It was a century that started with horses, simple automobiles, and freighters but ended with high-speed rail, cruise ships, global commercial air travel and the Space Shuttle. Horses and other pack animals, every society's basic form of personal transportation for thousands of years, were replaced by automobiles and buses within a few decades. These developments were made possible by the exploitation of fossil fuel resources, which offered energy in an easily portable form, but also caused concern about pollution and long-term impact on the environment. Humans explored space for the first time, taking their first footsteps on the Moon.
Mass media, telecommunications, and information technology (especially computers, paperback books, public education, and the Internet) made the world's knowledge more widely available. Public health improvements led to global life expectancy increasing from 35 years to 65 years. Rapid technological advancements, however, also allowed warfare to reach unprecedented levels of destruction. World War II alone killed over 60 million people, while nuclear weapons gave humankind the means to annihilate itself in a short time. However, these same wars resulted in the destruction of the imperial system. For the first time in human history, empires and their wars of expansion and colonization ceased to be a factor in international affairs, resulting in a far more globalized and cooperative world. The last time major powers clashed openly was in 1945, and since then, violence has seen an unprecedented decline.
Fascism, a movement which grew out of post-war angst and which accelerated during the Great Depression of the 1930s, gained momentum in Italy, Germany, and Spain in the 1920s and 1930s, culminating in World War II, sparked by Nazi Germany's aggressive expansion at the expense of its neighbors. Meanwhile, Japan had rapidly transformed itself into a technologically advanced industrial power and, along with Germany and Italy, formed the Axis powers. Japan's military expansionism in East Asia and the Pacific Ocean brought it into conflict with the United States, culminating in a surprise attack which drew the US into World War II.
Following World War II, the United Nations, successor to the League of Nations, was established as an international forum in which the world's nations could discuss issues diplomatically. It enacted resolutions on such topics as the conduct of warfare, environmental protection, international sovereignty, and human rights. Peacekeeping forces consisting of troops provided by various countries, with various United Nations and other aid agencies, helped to relieve famine, disease, and poverty, and to suppress some local armed conflicts. Europe slowly united, economically and, in some ways, politically, to form the European Union, which consisted of 15 European countries by the end of the 20th century.
At the beginning of the century, strong discrimination based on race and sex was significant in most societies. Although the Atlantic slave trade had ended in the 19th century, movements for equality for non-white people in the white-dominated societies of North America, Europe, and South Africa continued. By the end of the 20th century, in many parts of the world, women had the same legal rights as men, and racism had come to be seen as unacceptable, a sentiment often backed up by legislation. When the Republic of India was constituted, the disadvantaged classes of the caste system in India became entitled to affirmative action benefits in education, employment and government.
Attitudes toward pre-marital sex changed rapidly in many societies during the sexual revolution of the 1960s and 1970s. Attitudes towards homosexuality also began to change in the later part of the century.
Economic growth and technological progress had radically altered daily lives. Europe appeared to be at a sustainable peace for the first time in recorded history. The people of the Indian subcontinent, a sixth of the world population at the end of the 20th century, had attained an indigenous independence for the first time in centuries. China, an ancient nation comprising a fifth of the world population, was finally open to the world, creating a new state after the near-complete destruction of the old cultural order. With the end of colonialism and the Cold War, nearly a billion people in Africa were left in new nation states.
The world was undergoing its second major period of globalization; the first, which started in the 18th century, having been terminated by World War I. Since the US was in a dominant position, a major part of the process was Americanization. The influence of China and India was also rising, as the world's largest populations were rapidly integrating with the world economy.
Terrorism, dictatorship, and the spread of nuclear weapons were pressing global issues. The world was still blighted by small-scale wars and other violent conflicts, fueled by competition over resources and by ethnic conflicts.
Disease threatened to destabilize many regions of the world. New viruses such as the West Nile virus continued to spread. Malaria and other diseases affected large populations. Millions were infected with HIV, the virus which causes AIDS. The virus was becoming an epidemic in southern Africa.
Based on research done by climate scientists, the majority of the scientific community consider that in the long term environmental problems pose a serious threat. One argument is that of global warming occurring due to human-caused emission of greenhouse gases, particularly carbon dioxide produced by the burning of fossil fuels. This prompted many nations to negotiate and sign the Kyoto treaty, which set mandatory limits on carbon dioxide emissions.
The number of people killed during the century by government actions was in the hundreds of millions. This includes deaths caused by wars, genocide, politicide and mass murders. The deaths from acts of war during the two world wars alone have been estimated at between 50 and 80 million. Political scientist Rudolph Rummel estimated 262,000,000 deaths caused by democide, which excludes those killed in war battles, civilians unintentionally killed in war and killings of rioting mobs. According to Charles Tilly, "Altogether, about 100 million people died as a direct result of action by organized military units backed by one government or another over the course of the century. Most likely a comparable number of civilians died of war-induced disease and other indirect effects." It is estimated that approximately 70 million Europeans died through war, violence and famine between 1914 and 1945.
After gaining political rights in the United States and much of Europe in the first part of the century, and with the advent of new birth control techniques, women became more independent throughout the century.
A violent civil war broke out in Spain in 1936 when General Francisco Franco rebelled against the Second Spanish Republic. Many consider this war as a testing battleground for World War II, as the fascist armies bombed some Spanish territories.
In 1948 The Nakba was, according to several historians, a targeted ethnic cleansing campaign against Arabs in Palestine perpetrated by Jewish Militias under Plan Delta, a plan ordered by Ben-Gurion. The campaign utilized methods of intimidation, violent attacks, and the destruction of several Arab villages.
The Soviet authorities caused the deaths of millions of their own citizens to eliminate domestic opposition. More than 18 million people passed through the Gulag, with a further 6 million being exiled to remote areas of the Soviet Union.
The Tiananmen Square protests of 1989, culminating in the deaths of hundreds of civilian protesters, were a series of demonstrations in and near Tiananmen Square in Beijing, China. Led mainly by students and intellectuals, the protests occurred in a year that saw the collapse of a number of communist governments around the world.
European integration began in earnest in the 1950s, and eventually led to the European Union, a political and economic union that comprised 15 countries at the end of the 20th century.
As the century began, Paris was the artistic capital of the world, where both French and foreign writers, composers and visual artists gathered. By the middle of the century New York City had become the artistic capital of the world.
Theater, films, music and the media had a major influence on fashion and trends in all aspects of life. As many films and much music originate from the United States, American culture spread rapidly over the world.
The invention of music recording technologies such as the phonograph record, and dissemination technologies such as radio broadcasting, massively expanded the audience for music. Prior to the 20th century, music was generally only experienced in live performances. Many new genres of music were established during the 20th century.
Modern dance is born in America as a 'rebellion' against centuries-old European ballet. Dancers and choreographers Alvin Ailey, Isadora Duncan, Vaslav Nijinsky, Ruth St. Denis, Mahmoud Reda, Martha Graham, José Limón, Doris Humphrey, Merce Cunningham, and Paul Taylor re-defined movement, struggling to bring it back to its 'natural' roots and along with Jazz, created a solely American art form. Alvin Ailey is credited with popularizing modern dance and revolutionizing African-American participation in 20th-century concert dance. His company gained the nickname "Cultural Ambassador to the World" because of its extensive international touring. Ailey's choreographic masterpiece Revelations is believed to be the best known and most often seen modern dance performance.
Art Nouveau began as a form of architecture and design but fell out of fashion after World War I. The style was dynamic and inventive but unsuited to the depression of the Great War.
In Europe, modern architecture departed from the decorated styles of the Victorian era. Streamlined forms inspired by machines became commonplace, enabled by developments in building materials and technologies. Before World War II, many European architects moved to the United States, where modern architecture continued to develop.
The automobile increased the mobility of people in the Western countries in the early-to-mid-century, and in many other places by the end of the 20th century. City design throughout most of the West became focused on transport via car.
The popularity of sport increased considerably—both as an activity for all and as entertainment, particularly on television.
The modern Olympic Games, first held in 1896, grew to include tens of thousands of athletes in dozens of sports.
The FIFA World Cup was first held in 1930 and was held every four years after World War II.
American League Baseball was formed in 1900 and in 1903, both National and American agreed to play in the first World Series with over 100,000 in attendance.
Boxing, also known as "Prize Fighting" became popular over this decade although bare-knuckle fighting was still popular.
Radiocarbon dating was invented, and became a powerful technique for determining the age of prehistoric animals and plants as well as historical objects.
A much better understanding of the evolution of the universe was achieved, its age (about 13.8 billion years) was determined, and the Big Bang theory on its origin was proposed and generally accepted.
The age of the Solar System, including Earth, was determined, and it turned out to be much older than believed earlier: more than 4 billion years, rather than the 20 million years suggested by Lord Kelvin in 1862.
The planets of the Solar System and their moons were closely observed via numerous space probes. Pluto was discovered in 1930 on the edge of the solar system, although in the early 21st century, it was reclassified as a dwarf planet instead of a planet proper, leaving eight planets.
No trace of life was discovered on any of the other planets orbiting the Sun (or elsewhere in the universe), although it remained undetermined whether some forms of primitive life might exist, or might have existed, somewhere in the Solar System. Extrasolar planets were observed for the first time.
Norman Borlaug fathered the Green Revolution, the set of research technology transfer initiatives occurring between 1950 and the late 1960s that increased agricultural production in parts of the world, beginning most markedly in the late 1960s, and is often credited with saving over a billion people worldwide from starvation.
Changes in food production, along with sedentary lifestyles due to labor-saving devices and the increase in home entertainment, contributed to an "epidemic" of obesity, at first in the rich countries, but by the end of the 20th century spreading to the developing world.
Widespread use of petroleum in industry—both as a chemical precursor to plastics and as a fuel for the automobile and airplane—led to the geopolitical importance of petroleum resources. The Middle East, home to many of the world's oil deposits, became a center of geopolitical and military tension throughout the latter half of the century. (For example, oil was a factor in Japan's decision to go to war against the United States in 1941, and the oil cartel, OPEC, used an oil embargo of sorts in the wake of the Yom Kippur War in the 1970s).
In the last third of the century, concern about humankind's impact on the Earth's environment made environmentalism popular. In many countries, especially in Europe, the movement was channeled into politics through Green parties. Increasing awareness of global warming began in the 1980s, commencing decades of social and political debate.
Engineering and technology
One of the prominent traits of the 20th century was the dramatic growth of technology. Organized research and practice of science led to advancement in the fields of communication, electronics, engineering, travel, medicine, and war.
The first airplane, the Wright Flyer, was flown in 1903. With the engineering of the faster jet engine in the 1940s, mass air travel became commercially viable.
The assembly line made mass production of the automobile viable. By the end of the 20th century, billions of people had automobiles for personal transportation. The combination of the automobile, motor boats and air travel allowed for unprecedented personal mobility. In western nations, motor vehicle accidents became the greatest cause of death for young people. However, expansion of divided highways reduced the death rate.
New materials, most notably stainless steel, Velcro, silicone, teflon, and plastics such as polystyrene, PVC, polyethylene, and nylon came into widespread use for many various applications. These materials typically have tremendous performance gains in strength, temperature, chemical resistance, or mechanical properties over those known prior to the 20th century.
Aluminum became an inexpensive metal and became second only to iron in use.
Thousands of chemicals were developed for industrial processing and home use.
In addition to human spaceflight, uncrewed space probes became a practical and relatively inexpensive form of exploration. The first orbiting space probe, Sputnik 1, was launched by the Soviet Union in 1957. Over time, a massive system of artificial satellites was placed into orbit around Earth. These satellites greatly advanced navigation, communications, military intelligence, geology, climate, and numerous other fields. Also, by the end of the 20th century, uncrewed probes had visited or flown by the Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and various asteroids and comets, with Voyager 1 being the farthest manufactured object from Earth at 23,5 billion kilometers away from Earth as of 6 September 2022, and together with Voyager 2 both carrying The Voyager Golden Record containing sounds, music and greetings in 55 languages as well as 116 images of nature, human advancement, space and society.
The Hubble Space Telescope, launched in 1990, greatly expanded our understanding of the Universe and brought brilliant images to TV and computer screens around the world.
The Global Positioning System, a series of satellites that allow land-based receivers to determine their exact location, was developed and deployed.
^IPCC AR5 WG1 2013, "Summary for Policymakers, Observed Changes in the Climate System", pp. 10–11: "Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750." (p 11). "From 1750 to 2011, CO2 emissions from fossil fuel combustion and cement production have released 375 [345 to 405] GtC to the atmosphere, while deforestation and other land use change are estimated to have released 180 [100 to 260] GtC." (p. 10).
^Brown, DeNeen L. (October 22, 2019). "HBO's 'Watchmen' depicts a deadly Tulsa race massacre that was all too real". Washington Post. Retrieved July 3, 2020. "White city police officer "deputized" members of the lynch mob and "instructed them to get a gun and get a n-----", according to the Oklahoma Historical Society".
^"Tulsa race massacre of 1921 | Commission, Facts, & Books". Britannica. Retrieved September 4, 2022.