What factors led to a population boom in the northeastern cities?

The population boom in northeastern cities was primarily driven by industrialization, which created numerous job opportunities, attracting migrants from rural areas and other regions. Additionally, the influx of immigrants, particularly from Europe in the late 19th and early 20th centuries, contributed significantly to urban growth. Improved transportation systems, such as railroads, facilitated movement to cities, while advancements in healthcare and sanitation reduced mortality rates, further supporting population increases. Lastly, economic opportunities and the promise of a better life drew many to urban centers, solidifying their growth.