1. After mapping 1860
1. What physical features hindered or slowed down the diffusion of people Westward?
2. What role did water play in the formation of cities?
Appalachians
All major cities near water

2. After mapping 1900
3. What factors led to there being a west coast city (San Francisco) on the map?
4. Why were people moving West?
Immigration from Asia, the Transcontinental RR ( )
Gold Rush, open land

3. After mapping 1960
5. How did air-conditioning (more prominent after WWII) impact the location of the Top 10 cities?
Opened the south to larger scale settlement

4. After mapping 1990 and 2015
6. Describe the distribution of the Top 10 cities today.
7. What general, cardinal directions has the population center of the U.S. moved since 1860?
8. Why might some cities have dropped out of the Top 10 in the last 25 years?
9. What city do you think will be the next to drop out? Why?
10. What city do you think will be the next to join the Top 10? Why?