Change in Agriculture: The Northern United States, 1820–1870

American agriculture changed radically between 1820 and 1870. In turning slowly from subsistence to commercial farming, farmers on the average doubled the portion of their production places on the market, and thereby laid the foundations for today's highly productive agricultural industry. But the modern system was by no means inevitable. It evolved slowly through an intricate process in which innovative and imitative entrepreneurs were the key instruments.