By the 1840s, the Industrial Revolution was transforming the Northeast, with a dense network of railroads, canals, textile mills, small industrial cities, and growing commercial centers, with hubs in Boston, New York City, and Philadelphia. Although manufacturing interests, especially in Pennsylvania, sought a high tariff, the actual tariff in effect was low, and was reduced several times, with the 1857 tariff the lowest in decades. The Midwest region, based on farming and increasingly on animal production, was growing rapidly, using the railroads and river systems to ship food to slave plantations in the south, industrial cities in the East, and industrial cities in Britain and Europe.