The population grew rapidly as immigrants, mostly from Germany and Ireland, continued to arrive. The wealthy finally moved west of 7th Street, and the poor moved into their former homes near the Delaware River, many of which were now converted into tenements and boarding houses. With crowded row houses filling tiny streets and alleys, this area grew filthy and smelly—like areas of London that Penn hoped his city would never resemble.

During the 1840s and 1850s, hundreds of people died each year from malaria, smallpox, tuberculosis, and cholera. The poor were affected the worst because when disease broke out in the city, the rich found respite in second homes in areas like Germantown. Violence, lawlessness, and gangs became serious problems during these years. Many of the volunteer fire companies were infiltrated by gangs, and brutal fights broke out between rival gangs at fire sites, all wanting to be paid for putting out the fire.

As the city grew into an industrial metropolis, ethnic tensions also grew. In addition to the Swedish, German, and British immigrants who had first established homes in the city, Philadelphia was home to strong Irish Catholic and African American communities in the early part of the 19th century. These communities established mutual aid societies, churches, and other institutions, while facing a great deal of opposition from the Nativists of the time. Rampant racism and violence against immigrants, especially Irish Catholics, was common in the 1840s and 1850s. The Nativist Riots between Protestant Nativists and Irish Catholic immigrants began in 1844 over a question of religious practice in public schools and resulted in injury, death, and much property damage. Violence against African Americans was common, and African American homes and churches were sometimes burned.

The city didn’t have the structure or government in place to handle all its problems, and additional tax revenue was required to put programs and institutions—including a police force—in place. The Act of Consolidation was passed on February 2, 1854, which united all of Philadelphia County’s districts, townships, and municipalities into one big city. Through this act, 5 of the 30 largest cities in the country at the time were formed into a single municipality. This dramatically increased the size and tax base of the city, and the population grew from about 125,000 to more than 500,000. The total area of the city grew from 2 square miles to 129 square miles. In addition to the crowded area along the Delaware, there were more than 1,500 farms, woods, and wetlands in Philadelphia’s new boundaries. The city included the townships and villages (which we now know as neighborhoods) of Germantown, Manayunk, Roxborough, Frankford, Northern Liberties, and Kingsessing. Enough money would be generated to pay the new and much-needed police force, as well as many other public services including water, streets, and transportation.