- Increased immigration from Europe and other countries
- Overcrowding and poor sanitation
- Development of new forms of transportation, such as streetcars and subways
- Construction of skyscrapers
- Emergence of new social classes, such as the middle class and the working class
- Increased political and economic power of cities
- Rise of social and political reform movements
- Improvements in public health and education
- Development of new cultural institutions, such as museums, theaters, and libraries