45
Lesson 45 of 84 · Westward Expansion
The Mexican-American War
The Columbian Exchange transferred plants, animals, diseases, and ideas between the Americas and Europe after 1492. Potatoes went to Europe; horses and wheat came to the Americas.
Key Facts
1
Timelines show events in order.
2
Cause and effect explain why things happen.
3
Oral histories preserve community stories.
Check Your Understanding
Question 1
1 of 2Which is a secondary source?