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 20th century was dominated by significant geopolitical events that reshaped the political and social structure of the globe: World War I, the Spanish flu pandemic, World War II and the Cold War. Unprecedented advances in science and technology defined the modern era, including the advent of nuclear weapons and nuclear power, space exploration, the shift from analog to digital computing and the continuing advancement of transportation, including powered flight and the automobile. The Earth's sixth mass extinction event, the Holocene extinction, continued, and human conservation efforts increased.
Major themes of the century include decolonization, nationalism, globalization and new forms of intergovernmental organizations. Cultural homogenization began through developments in emerging transportation and information and communications technology. Poverty was reduced, and the century saw rising standards of living, world population growth, awareness of environmental degradation and ecological extinction. Automobiles, airplanes and home appliances became common, and video and audio recording saw mass adoption. Great advances in electricity generation and telecommunications allowed for near-instantaneous worldwide communication, ultimately leading to the Internet. Meanwhile, advances in medical technology resulted in the near-eradication and eradication of many infectious diseases, as well as opening the avenue of biological genetic engineering.
The conclusion of World War I and the resulting Treaty of Versailles saw the United Kingdom, France, Italy, the United States and Japan as the main arbiters of the new world order. Germany returned as a great power in 1933, when the Nazi Party replaced the Weimar Republic as the new government of Germany. In 1945, Nazi Germany officially surrendered, and the country was divided in two (the capitalist West Germany and the socialist East Germany, only reuniting at the end of the century). The end of World War II saw the United States, France, United Kingdom, Soviet Union and the Republic of China emerging as the primary victors. Political pressures from the United States, the Soviet Union, and the United Nations led France and the United Kingdom to withdraw from Egypt during the Suez Crisis. The episode demonstrated to the world that the United Kingdom and France had ceased to be global superpowers.
The repercussions of the World Wars, the Cold War, and globalization crafted a world where people were more united than any previous time in human history, as exemplified by the establishment of international law, international aid and the United Nations. The Marshall Plan—which spent US$13 billion ($110 billion in 2021 dollars) to rebuild the economies of post-war nations—launched “Pax Americana”. Throughout the latter half of the 20th century, the rivalry between the United States and the Soviet Union created enormous tensions around the world, which manifested in various armed proxy regional conflicts and the omnipresent danger of nuclear proliferation. The dissolution of the Soviet Union in 1991 after the revolutions of 1989 resulted in the United States emerging as the world's sole remaining superpower. China began rising rapidly as an economic and geopolitical power after the USSR's collapse.
It took over 200,000 years of modern human history and 6 million years of human evolution for the world's population to reach 1 billion in 1804. By 1927, the world population had reached an estimated 2 billion, and by late 2000, it had reached 6 billion, with over half of that in East, South, and Southeast Asia. Global literacy averaged 80%. Penicillin and other medical breakthroughs, combined with the World Health Organization's global vaccination campaigns, yielded unprecedented results, helping to eradicate smallpox and other diseases responsible for more human deaths than all wars and natural disasters combined; smallpox now only existed in labs. Machines came to be used in all areas of production, feeding increasingly intricate supply chains that allowed humankind for the first time to be constrained not by how much it could produce, but by consumption. Trade improvements greatly expanded upon the limited set of food-producing techniques used since the Neolithic period, multiplying the diversity of foods available and boosting the quality of human nutrition. Until the early 19th century, life expectancy from birth was about thirty in most populations; global lifespan averages exceeded 40 years for the first time in history, with over half achieving 70 or more years (three decades longer than a century earlier).
Overview[]
Main article: 20th-century events
For a chronological guide, see Timeline of the 20th century.
Chronological history[]
The 20th century began on 1 January 1901, and ended on 31 December 2000. It was the last century of the 2nd millennium. Unlike most century years, the year 2000 was a leap year, and the second century leap year in the Gregorian calendar after 1600.
The century had the first global-scale total wars between world powers across continents and oceans in World War I and World War II. Nationalism became a major political issue in the world in the 20th century, acknowledged in international law along with the right of nations to self-determination, official decolonization in the mid-century, and related regional conflicts.
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.
The world also became more culturally homogenized than ever with developments in transportation and communications technology, popular music and other influences of Western culture, international corporations, and what was arguably a truly global economy by the end of the 20th century.
Summary[]
At the beginning of the period, the British Empire was the world's most powerful nation, having acted as the world's policeman for the past century.
Technological advancements during World War I changed the way war was fought, as new inventions such as tanks, chemical weapons, and aircraft modified tactics and strategy. After more than four years of trench warfare in Western Europe, and up to 22 million dead, the powers that had formed the Triple Entente (France, Britain, and Russia, later replaced by the United States and joined by Italy and Romania) emerged victorious over the Central Powers (Germany, Austria-Hungary, the Ottoman Empire and Bulgaria). In addition to annexing many of the colonial possessions of the vanquished states, the Triple Entente exacted punitive restitution payments from them, plunging Germany in particular into economic depression. The Austro-Hungarian and Ottoman empires were dismantled at the war's conclusion. The Russian Revolution resulted in the overthrow of the Tsarist regime of Nicholas II and the onset of the Russian Civil War. The victorious Bolsheviks then established the Soviet Union, the world's first communist state.
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.
After some years of dramatic military success, Germany was defeated in 1945, having been invaded by the Soviet Union and Poland from the East and by the United States, the United Kingdom, Canada, and France from the West. After the victory of the Allies in Europe, the war in Asia ended with the Soviet invasion of Manchuria and the dropping of two atomic bombs on Japan by the US, the first nation to develop nuclear weapons and the only one to use them in warfare. In total, World War II left some 60 million people dead.
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.
After the war, Germany was occupied and divided between the Western powers and the Soviet Union. East Germany and the rest of Eastern Europe became Soviet puppet states under communist rule. Western Europe was rebuilt with the aid of the American Marshall Plan, resulting in a major post-war economic boom, and many of the affected nations became close allies of the United States.
With the Axis defeated and Britain and France rebuilding, the United States and the Soviet Union were left standing as the world's only superpowers. Allies during the war, they soon became hostile to one another as their competing ideologies of communism and democratic capitalism proliferated in Europe, which became divided by the Iron Curtain and the Berlin Wall. They formed competing military alliances (NATO and the Warsaw Pact) which engaged in a decades-long standoff known as the Cold War. The period was marked by a new arms race as the USSR became the second nation to develop nuclear weapons, which were produced by both sides in sufficient numbers to end most human life on the planet had a large-scale nuclear exchange ever occurred. Mutually assured destruction is credited by many historians as having prevented such an exchange, each side being unable to strike first at the other without ensuring an equally devastating retaliatory strike. Unable to engage one another directly, the conflict played out in a series of proxy wars around the world—particularly in China, Korea, Cuba, Vietnam, and Afghanistan—as the USSR sought to export communism while the US attempted to contain it. The technological competition between the two sides led to substantial investment in research and development which produced innovations that reached far beyond the battlefield, such as space exploration and the Internet.
In the latter half of the century, most of the European-colonized world in Africa and Asia gained independence in a process of decolonization. Meanwhile, globalization opened the door for several nations to exert a strong influence over many world affairs. The US's global military presence spread American culture around the world with the advent of the Hollywood motion picture industry and Broadway, jazz, rock music, and pop music, fast food and hippy counterculture, hip-hop, house music, and disco, as well as street style, all of which came to be identified with the concepts of popular culture and youth culture. After the Soviet Union collapsed under internal pressure in 1991, most of the communist governments it had supported around the world were dismantled—with the notable exceptions of China, North Korea, Cuba, Vietnam, and Laos—followed by awkward transitions into market economies.
Nature of innovation and change[]
Due to continuing industrialization and expanding trade, many significant changes of the century were, directly or indirectly, economic and technological in nature. Inventions such as the light bulb, the automobile, and the telephone in the late 19th century, followed by supertankers, airliners, motorways, radio, television, air conditioning, antibiotics, nuclear power, frozen food, computers and microcomputers, the Internet, and mobile telephones affected people's quality of life across the developed world. The quantity of goods consumed by the average person expanded massively. Scientific research, engineering professionalization and technological development—much of it motivated by the Cold War arms race—drove changes in everyday life.
Social change[]
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.
Earth at the end of the 20th century[edit][]
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.
World population increased from about 1.6 billion people in 1901 to 6.1 billion at the century's end.