A city that governs itself and the lands surrounding it; it functions like an independent country

The correct answers are A) the Industrial Revolution and B) major technological advancements.

The changes that American experienced during the second half of the 19th century were the Industrial Revolution and major technological advancements.

On the second half of the 1800s, the United States lived in a moment of transformation in the industrial business. Many technological advances allow the Industrial Revolution to flourish, impacting many people's lives. Factories had new machines to have mass production, which meat to produce more goods in less time, at low costs. Factories demanded workers. So many people from the rural states moved to larger cities because they were looking for better jobs and better living conditions for their families.