The document discusses several key inventions and economic developments in the United States including the national market, cotton gin, steel plow, mechanical reaper, telegraph, and rise of cotton and slavery in the South. The national market boosted the economy by exporting goods abroad. The cotton gin automated and increased cotton production, fueling the demand for slavery. The steel plow and mechanical reaper increased agricultural productivity. The telegraph allowed rapid communication. Cotton became the dominant crop and economic driver of the South, further entrenching the institution of slavery. Nativism emerged as Americans resented immigrants taking jobs.