Final answer:
White people in the Northern United States gained their fortunes through business ventures, investments, and industrialization during the 19th century.
Step-by-step explanation:
In the Northern United States, many white people gained their fortunes through various means, including business ventures, investments, and industrialization.
During the 19th century, the industrial revolution brought about significant economic growth in the North. This led to the rise of industries such as manufacturing, mining, and transportation, providing opportunities for individuals to accumulate wealth.
For example, entrepreneurs like Andrew Carnegie and John D. Rockefeller became extremely wealthy through their investments in industries such as steel and oil, respectively. These individuals demonstrated the potential for financial success through astute business strategies and advancements in technology.