First one to answer will get branliest. case study: the very big apple with over eight million people, new york city is the most heavily populated city in the u. s. between 1800 and 1900, the population of new york increased from about 80,000 to over three million people. in the years after the civil war, the population of new york city tripled. with a large influx of european immigrants new york became known as the "melting pot." new york has always had the highest population density of any u. s. city. according to the 2000 census, new york city has about 26,403 people per square mile—almost twice the number of people per mile as chicago. in the years after the civil war, the population of new york city tripled. what can you infer about why there was such a large increase in the population? people migrated from smaller towns to cities to find work. people felt that rural areas were no longer a safe place to live. people were interested in the culture that was available in cities. people moved closer together to show that the country was united.