Landforms and Waterways
What formed many of the landforms in the United States?
Glaciers and tectonic activity
What is the Continental Divide?
A high point in the Rocky Mountains determining river flow
Who was the first European group to reach North America?
The Vikings
What was the Underground Railroad?
A secret network to help enslaved people escape
Why is acid rain harmful?
It corrodes buildings and harms crops
Which mountain range is the tallest in North America?
Alaska Range
The Great Lakes were formed by what natural force?
Glaciers
What are colonies?
Overseas settlements tied to a parent country
What is dry farming?
Growing crops relying only on natural precipitation
Smog is mainly caused by what?
Chemical pollution in the air
The Great Plains stretch between which two landforms?
The Appalachian and the Rockies
What is a rain shadow?
An area where mountains block rain from reaching the interior
Why did Europeans colonize North America?
To find valuable resources and land
What is population density?
The number of people per square mile
The U.S. consumes how much freshwater daily per household?
400 gallons
Which river is the longest in North America?
Missouri River
The Everglades are an example of what ecosystem?
A swampy wetland
The U.S. War for Independence was fought against which country?
England
What type of economy does the U.S. have?
Free market economy
Overfishing threatens what?
Fish populations
What are tributaries?
Small rivers that feed into larger rivers
The first people to migrate to North America came from what continent?
Asia
What event doubled the size of the United States?
The Louisiana Purchase
What is clear-cutting?
Cutting down entire forests
What are cash crops?
Crops grown specifically for profit