Final answer:
The Northeast was the most industrial region in the mid-1800s, becoming the center of the Industrial Revolution in the United States with the development of textiles, metals, and automobile manufacturing.
Step-by-step explanation:
The area that was more industrial in the mid-1800s was c.) the Northeast. The Industrial Revolution began in Great Britain and soon after spread to the United States, where it took a firm hold in the Northeast around the Great Lakes, known as the Manufacturing Belt. This region witnessed rapid industrial growth led by mechanized manufacturing of textiles in New England, followed by steel and other metals in Pennsylvania and Indiana, and later, the manufacturing of automobiles in Michigan.
The progress in manufacturing was significantly supported by resources like coal mining, particularly in western Pennsylvania and Appalachia, necessary for supplying power to the industries. Cities in the Northeast thrived around these industries and benefited from advancements in the transportation revolution, which helped mobilize resources and distribute goods. This contrasted sharply with the predominantly agrarian South, which was not as industrialized.
Therefore, the Northeast was the epicenter of America's Industrial Age, marking a shift from an agrarian economy to an industrial one, with urban culture and a growing middle class emerging from these advancements.