What was the underground railroad? (What was--?)

Series: What was--?

• What was Pearl Harbor?

• What was the Alamo?

• What was the Battle of Gettysburg?

• What was the Boston Tea Party?

• What was the first Thanksgiving?

• What was the Gold Rush?

• What was the March on Washington?

• What was the underground railroad?

• What is the Panama Canal?

• What is the Statue of Liberty?

• What was Ellis Island?

• What was Pompeii?

• What was the Hindenburg?

• What was the Lewis and Clark Expedition?

• What is the Super Bowl?

• What is the World Series?

• What was D-Day?

• What was Hurricane Katrina?

• What was the Great Depression?

• What were the Salem Witch Trials?

• What are the Summer Olympics?

• What is the Declaration of Independence?

• What was the Great Chicago Fire?

• What was the San Francisco Earthquake?

• What was Woodstock?

• What were the Twin Towers?

• What are the ten commandments?

• What is rock and roll?

• What was the Age of the Dinosaurs?

• What was the Ice Age?

• What is climate change?