Cities in the United States grew by approximately 15 million people between 1880 and 1900, which led to radical changes in city life, including noise, traffic, slums, air pollution and sanitation problems. This explosion in population was largely a result of industrial expansion.
The look of cities also changed, with mass transit systems, such as trolleys, subways and cable cars, and the construction of skyscrapers. Additionally, suburbs were introduced to the areas around urban centers in order to house the new populations of commuters. Those people living within the cities generally lived in apartments and tenements,and some areas became close-knit enclaves for immigrant populations.
Chinese immigrants were commonplace in San Francisco, which had attracted them with the promise of gold fortunes. Most were single males who wished to return home after making their fortune.
The new type of immigrants, who previously tended to be British and European, contributed to enhanced ethnic diversity in American cities, coming from parts of southern and eastern Europe including Italy, Slovenia, Croatia, Slovakia, Poland, Hungary, Romania, Russia and Greece. In large cities, such as New York and Chicago, the areas in which these groups settled came to be known by new names, such as "Little Italy," "Little Hungary," and so forth.