An especially prominent example of large-scale internal migration is the opening of the American West. At the time of independence, the United States consisted of long-established settlements concentrated on the Atlantic Coast and a scattering of newer settlements in the territories west of the Appalachian Mountains. Through mass interregional migration, the interior of the continent was settled and developed.
The U.S. Census Bureau computes the country’s population center at the time of each census. The population center is the average location of everyone in the country, the “center of population gravity.” If the United States were a flat plane placed on top of a pin, and each individual weighed the same, the population center would be the point where the population distribution causes the flat plane to balance on the pin.
The changing location of the population center graphically demonstrates the march of the American people across the North American continent over the past 200 years. The center has consistently shifted westward, although the rate of movement has varied in different eras.
The population center is the average location of everyone in the country, the “center of population gravity.” If the United States were a flat plane placed on top of a pin, and each individual weighed the same, the population center would be the point where the population distribution causes the flat plane to balance on the head of a pin.
This location reflects the fact that virtually all colonial-era settlements were near the Atlantic Coast. Few colonists ventured far from coastal locations because they depended on shipping links with Europe to receive products and to export raw materials. The Appalachian Mountains also initially hindered western development because of their steep slopes, thick forests, and few gaps that allowed easy passage. Native Americans still occupied large areas and sometimes resisted the expansion of colonial settlement.
Transportation improvements, especially the building of canals in the northeast, helped to open the interior. Most important was the Erie Canal, which enabled people to travel inexpensively by boat between New York City and the Great Lakes. In 1840, the United States had 5,352 kilometers (3,326 miles) of canals. Encouraged by the opportunity to obtain a large amount of land at a low price, people moved into forested river valleys between the Appalachians and the Mississippi River. They cut down the trees and used the wood to build homes, barns, and fences.
The population center shifted westward more rapidly during this period. Rather than continuing to expand agriculture into the next available westward land, mid-nineteenth-century pioneers kept going all the way to California. The principal pull to California was the Gold Rush, beginning in the late 1840s. Pioneers during this period also passed over the Great Plains because of the physical environment. The region’s dry climate, lack of trees, and tough grassland sod convinced leaders such as Thomas Jefferson and explorers such as Zebulon Pike that the region was a desert unfit for farming. Government maps at the time labeled the Great Plains as the Great American Desert.
The westward movement of the U.S. population center slowed during this period because emigration from Europe to the East Coast offset most of the emigration from the East Coast to the U.S. West. Also, immigrants began to fill in the Great Plains that earlier generations had bypassed (Figure 3-15). Advances in agricultural technology enabled people to cultivate the area. Farmers used barbed wire to reduce dependence on wood fencing, the steel plow to cut the thick sod, and windmills and well-drilling equipment to pump more water. The expansion of the railroads encouraged settlement of the Great Plains. The federal government gave large land grants to the railroad companies, which were able to finance construction of their lines by selling portions to farmers. The extensive rail network then permitted settlers to transport their products to the large concentrations of customers in East Coast cities.
The population center resumed a more vigorous westward migration. It also moved southward, as Americans migrated to the South for job opportunities and a warmer climate. The rapid growth of population and employment in the South has aggravated interregional antagonism. Some industries have relocated from the Northeast and Midwest, but most of the South’s industrial growth comes from newly established companies. Interregional migration has slowed considerably in the United States into the twenty-first century (Figure 3-16). Regional differences in employment prospects have become less dramatic. The severe recession of 2008-09 discouraged people from migrating because of limited job prospects in all regions.
Interregional Migration In The United States, 2016–2017
How might climate change affect patterns of interregional migration in the United States?