1. The Industrial Revolution
   The Age of Revolution
2. The Civil War Era
   The Age of Imperialism

You have the American Civil War to thank, in large part, for both the fight to end slavery in the South and its abolishment by then-President Abraham Lincoln. Lincoln's Emancipation Proclamation declared "all persons held as slaves" to be free.

1. The Edwardian Age
   The Civil Rights Era
2. The Renaissance
   The Reconstruction Era

Martin Luther King Jr. was known for his work throughout the Civil Rights Era, a period that encompassed the mid-1950s to the late-1960s. The speech, which took place during the March on Washington, happened right in the middle — August 1963.

1. The 1960s
   The 1980s
2. The 1940s
   The 1930s

Over a three-day period on a dairy farm in Bethel, New York, more than 400,000 people participated in the Woodstock Music Festival. The event went down in August 1969, a concert dubbed "three days of peace and music."

1. The Gilded Age
   The American Revolution
2. The Elizabethan Period
   The Progressive Era

The Progressive Era, a time of great political change in the U.S. — from the late 1800s to the early 1900s — ushered in the 19th Amendment, granting women the right to vote. The amendment was passed by Congress in June 1919 and ratified a year later.

1. The American Revolution
   The American Civil War
2. The Victorian Age
   The Civil Rights Era

The Declaration of Independence was a central component of the period of time known as the American Revolution, which included the fledgling country's fight for independence from its British roots. The document was not officially signed until August 2, 1776.

1. The Enlightenment
   The Stone Age
2. The Roaring Twenties
   The Cold War

It may have been the Roaring Twenties, but it could've been called the "Dry Twenties" as well. The failed experiment known as Prohibition began in 1920 and continued until 1933 when the 21st Amendment nixed it.

1. The 1800s
   The 1960s
2. The 1920s
   The 1770s

The year was 1803 when then-President Thomas Jefferson helped broker a deal between the United States and France for a portion of land that would create 13 additional states in the U.S. Historically, it has been called the "greatest land deal ever."

1. The Romantic Era
   The Middle Ages
2. The Roaring 20s
   The Great Depression

Historians say the stock market crash of 1929 would be the equivalent of losing nearly $400 billion today. No wonder it led to a depression — the Great Depression, that is, an era that lasted until the mid-1930s.

1. The Romantic Era
   The Protestant Reformation
2. The Enlightenment
   The Renaissance

The Renaissance was a period of time in which the arts flourished. Michelangelo was one of those contributing to the movement. His work on the ceiling of the Sistine Chapel is still enjoyed by tourists from around the world who visit it today.

1. The Victorian Age
   The Progressive Era
2. The Reconstruction Era
   The Age of Enlightenment

It would've been extremely "progressive" in the period from the 1890s to the 1920s to have built an almost-900-ft.-long ship, but that's what the Titanic was until it struck an iceberg and sank in April 1912.

1. The 1940s
   The 1950s
2. The 1960s
   The 1970s

Four years after the attack on Pearl Harbor, U.S. troops detonated nuclear weapons over Hiroshima and Nagasaki, Japan. A few days later, on August 15, 1945, the Japanese surrendered, effectively marking the end of WWII.

1. The Information Age
   The Progressive Era
2. The Reconstruction Era
   The Edwardian Age

The first telephone, an invention of Alexander Graham Bell, was developed in 1876 — near the end of the period known as the Reconstruction Era. It was a period of rebuilding following the American Civil War.

1. The 2010s
   The 1840s
2. The 1940s
   The 1740s

The Great Famine in Ireland, when potato crops failed in the country, led to the deaths of roughly 1 million people and the emigration of another million. This famine, which occurred from 1845 to 1849, was the biggest in Europe during that time period.

1. The Edwardian Age
   The Victorian Age
2. The Elizabethan Period
   The Gilded Age

The Victorian Age, so named for the period of time when Queen Victoria reigned, encompassed the years from 1837 to 1901 in England. In the midst of that era, the country saw massive growth and expansion.

1. The Renaissance
   The Iron Age
2. The Cold War Era
   The Age of Revolution

While the Olympics date back as far as 776 BC, the first modern Olympic games were held in Greece during the Age of Revolution (1896, to be specific). The Age of Revolution marked a period of change in countries around the world.

1. The 1980s
   The 1910s
2. The 1970s
   The 1880s

The 1970s were a period of advancements for women following the "peace and love" era of the 1960s. It was also the decade that brought us the Watergate scandal, a black mark on then-President Richard Nixon's legacy.

1. 7th Century BC
   The Age of Enlightenment
2. The Industrial Revolution
   10th Century BC

The building of the 13,170 miles of the Great Wall of China began during the 7th Century BC and continued until almost the early 1900s. The early parts of the wall were built as a means of protection during periods of warring and invasions.

1. The 1980s
   The 1970s
2. The 1950s
   The 1960s

Many people who were alive when JFK was killed in November 1963 would tell you today that they remember exactly where they were when they heard the news. President John F. Kennedy was shot while riding in a motorcade in Dallas, Texas.

1. World War I
   World War II
2. The Vietnam War
   The Korean War

From 1941 to 1945 — the period of history that included World War II — more than 6 million Jewish men, women and children were killed in concentration camps at the direction of Adolph Hitler's Nazi regime.

1. The Great Depression
   The Civil Rights Movement
2. The Cold War
   The Information Age

The period of history known as the Cold War — which began in the late 1940s — encompassed a lot of history, including the moon landing. Neil Armstrong's few steps on the moon during this historic era prompted this memorable quote.

1. The 1970s
   The 1990s
2. The 1950s
   The 1980s

The period known as the Cold War effectively ended with the tearing down of the Berlin Wall. The wall's demolition started in June 1990 and was completed in November 1991. In June 1987, during a speech in West Berlin, then-President Ronald Reagan famously said, "Mr. Gorbachev, tear down this wall."

1. The Renaissance
   The Enlightenment
2. The Age of Discovery
   The First World War

The Renaissance was a resurgence for arts and culture, which makes it a fitting historical period for the invention of the modern printing press. Gutenberg's press was created in the mid-1400s in Germany.

1. The 1990s
   The 1970s
2. The 1980s
   The 2000s

You might have been tempted to say the 2000s (or even the 1990s) but it was the 1980s that gave us one of the world's biggest inventions of all time — the internet. Some of the foundational elements of the internet, however, can be traced back to the 1950s.

1. The American Revolution
   The Vietnam War
2. World War I
   The Korean War

The Cuban Missile Crisis happened in 1962, amid the Vietnam War and while President John F. Kennedy was still in office. The event was marked by the discovery of the Soviet Union's installation of nuclear weapons in Cuba.

1. The 1970s
   The 1980s
2. The 1990s
   The 2010s

Millions of people were watching when the Challenger exploded during the live telecast of its liftoff. Seven people, including teacher Christa McAuliffe, were killed just a little over one minute after the space shuttle launched.

1. The Age of Imperialism
   The Information Age
2. The Age of Discovery
   The Edwardian Age

The Information Age which, some may say still extends into today, could have begun as far back as the 1970s. The terrorist attacks of September 11, 2001, occurred during this period, with millions watching the events unfold as they happened.

1. The 1980s
   The 1990s
2. The 2000s
   The 2010s

Can you believe it has only been a little more than a decade since the first iPhone was released in 2007? Fast-forward 13 years and we've gone through various iterations of the smartphones and a whole new line of "smart" devices.

1. The Enlightenment
   The Renaissance
2. The Reformation
   The Revolution

Do you remember the childhood rhyme: "Back in 1492, Columbus sailed the ocean blue ..." This "discovery" occurred during the period known as the Renaissance. Of course, some believe the Americas were discovered much earlier. (Thanks, Leif Erikson!)

1. The Roaring Twenties
   The Great Depression
2. The Civil Rights Era
   The Cold War

It was the Roaring Twenties when Fleming made the discovery in a London hospital, something that changed the course of history — and our health — forever. In medical circles, this discovery ushered in the "era of antibiotics."

1. The Vietnam War
   World War I
2. World War II
   The Cold War

D-Day, also known as the Normandy landings, occurred on June 6, 1944, during World War II. On that day, more than 150,000 troops from North America and Europe landed on the coast of France, a turning point that led to the beginning of the end of the war.

1. The 1870s
   The 1920s
2. The 1980s
   The 1740s

The explosion at the Chernobyl Nuclear Power Plant in Ukraine took place in April 1986. Even today, there remain questions about the severity of its impact on the area surrounding its initial impact.

1. The Gilded Age
   The American Revolution
2. The Information Age
   The Cold War

The Cold War was a period of time that pitted the United States against the Soviet Union in many areas. One of those was the race to be first in space exploration, an era known as the "Space Race."

1. The American Civil War
   The American Revolution
2. The Industrial Revolution
   The Edwardian Age

The Boston Tea Party, the dumping of tea in the Boston Harbor to protest taxation without representation, occurred in 1773 — three years before the Declaration of Independence was signed during the American Revolution era.

1. The 1980s
   The 1990s
2. The 2010s
   The 2000s

The 2010s were a time of growth and change — a piece of the Information Age in which we currently live. In 2015, the United States Supreme Court legalized same-sex marriage in all 50 states.

1. The Civil Rights Era
   The Cold War
2. World War II
   The Industrial Revolution

The protests in Tiananmen Square in 1989 were student-led demonstrations of up to 1 million people lobbying for democracy and freedom of the press, among other things. Chinese troops pushed back against the protesters, killing estimates ranging from several hundred to several thousand people.