Although Democratic-Republicans initially hoped to limit the powers of the national government, the rapid growth of the United States pulled in the opposite direction. An increased population, combined with the exhaustion of farmland along the eastern seaboard, fueled migration to the West as well as the growth of cities. These developments heightened conflicts with Indians and over slavery, but they also encouraged innovations in transportation and communication and improvements in agriculture and manufacturing.

As white Americans encroached more deeply on lands long settled by native peoples, Indian tribes were forced ever westward. As early as 1800, groups like the Shoshone, who originally inhabited the Great Plains, had been forced into the Rocky Mountains by Indians moving into the plains from the Mississippi and Ohio valleys (Map 8.2). Sacagawea must have realized that the expedition she accompanied would only increase pressure on the Shoshone and other nations as white migration escalated.

Although the vast majority of Americans continued to live in rural areas, a growing number moved to cities as eastern farmland lost its fertility and young people sought job opportunities in manufacturing, skilled trades, and service work. Cities were defined at the time as places with 8,000 or more inhabitants, but New York City and Philadelphia both counted more than 100,000 residents by 1810. In New York, immigrants, most of them Irish, made up about 10 percent of the population in 1820 and twice that percentage five years later. At the same time, the number of African Americans in New York City increased to more than 10,000. Cities began to emerge along the nation’s frontier as well. After the Louisiana Purchase, New Orleans became a key commercial center while western migration fueled cities like Cincinnati. Even smaller frontier towns, like Rock Island, Illinois, served important functions for migrants traveling west. Trading posts appeared across the Mississippi valley, which eased the migration of thousands headed farther west. They served as sites of exchange between Indians and white Americans and created the foundations for later cities (Table 8.1).

Most Americans who headed west hoped to benefit from the increasingly liberal terms for land offered by the federal government. Yeomen farmers sought sufficient acreage to feed their families and grow some crops for sale. They were eager to settle in western sections of the original thirteen states, in the Ohio River valley, or in newly opened territories along the Missouri and Kansas Rivers. In the South, small farmers had to compete with slave-owning planters who headed west in the early nineteenth century. Migrants to the Mississippi valley also had to contend with a sizable population of Spanish and French residents, as well as Chickasaw and Creek Indians in the South and Shawnee, Chippewa, Sauk, and Fox communities farther north.

The development of roads and turnpikes hastened the movement of people and the transportation of goods. Frontier farmers wanted to get their produce to eastern markets quickly and cheaply. Before completion of the Lancaster Turnpike in Pennsylvania, it cost as much to carry wheat overland the sixty-two miles to Philadelphia as it did to ship it by sea from Philadelphia to London. Those who lived farther west faced even greater challenges. With the admission of Kentucky (1792), Tennessee (1796), and Ohio (1803) to the Union, demands for congressional support for building transportation routes grew louder. By 1819 five more states had been admitted along the Mississippi River, from Louisiana to Illinois.

During Jefferson’s administration, secretary of the treasury Albert Gallatin urged Congress to fund roads and canals to enhance the economic development of the nation. He advocated a “great turnpike road” along the Atlantic seaboard from Maine to Georgia as well as roads to connect the four main rivers that flowed from the Appalachians to the Atlantic Ocean. Although traditionally such projects were funded by the states, in 1815 Congress approved funds for a National Road from western Maryland through southwestern Pennsylvania to Wheeling, West Virginia. This so-called Cumberland Road was completed in 1818 and later extended into Ohio and Illinois.

Carrying people and goods by water was even faster and cheaper than transporting them over land, but rivers ran mainly north and south. In addition, although loads could be delivered quickly downstream, the return voyage was long and slow. While politicians advocated the construction of canals along east-west routes to link river systems, inventors and mechanics focused on building boats powered by steam to overcome the problems of sending goods upriver.

In 1804 Oliver Evans, a machinist in Philadelphia, invented a high-pressure steam engine attached to a dredge that cleaned the silt around the docks in Philadelphia harbor. He had insufficient funds, however, to pursue work on a steam-powered boat. Robert Fulton, a New Yorker, improved on Evans’s efforts, using the low-pressure steam engine developed in England. In 1807 Fulton launched the first successful steamboat, the Clermont, which traveled up the Hudson River from New York City to Albany in only thirty-two hours. The powerful Mississippi River proved a greater challenge, but by combining Evans’s high-pressure steam engine with a flat-bottom hull that avoided the river’s sandbars, mechanics who worked along the frontier improved Fulton’s design and launched the steamboat era in the West.