Why did Chicago become a major city?

Related questions

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4. Is it expensive to live in Chicago?
5. How did they raise Chicago?
6. Is Chicago Illinois Safe?
7. Who named Chicago?
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Tags

1. #grain
2. #european
3. #railroad
4. #chicago
5. #incorporated
6. #world
7. #reached
8. #immigrants
9. #largest
10. #first
11. #population
12. #residents
13. #telegraph