Migration was a persistent feature of life in West Virginia during the 20th century. Since the second decade of the century, when high birth rates led to continued growth of the overall state population, West Virginia suffered a net loss through migration—that is, more people left the state than moved in. After 1950, the birth rate declined and the pace of migration accelerated, leading to dramatic population losses at a time when the nation at large was growing rapidly. Though the 1970s saw a modest surge of return migration due to the national energy crisis and resulting coalfield prosperity, the outflow of people resumed in the 1980s and continued at a slow rate through the century's end.

Although migration itself was persistent, the sources and direction varied considerably at different times. During the first decades of the century, while coalfield and urban counties grew, rural counties that lacked extractive industries lost people. For example, a cluster of five Little Kanawha Valley counties lost four percent of its population between 1900 and 1910, followed the next decade by an eight percent loss. As the timber industry declined during the 1930s and 1940s, rural counties along the Virginia border suffered similar declines. Then in the 1950s and 1960s came the great flood of coalfield migrants, which, after a brief halt in the 1970s, continued through the end of the century. During the 1980s, deindustrialization affected the Ohio and Kanawha valleys, with the result that urban people for the first time joined the migrant stream.

Military recruiters and the draft during World War II and the Cold War unintentionally but effectively stimulated migration by introducing West Virginia soldiers to employment opportunities and diversions in all parts of the nation. Otherwise, migrant streams tended to flow along established paths. Thus during the early years of the century, farm youth from western West Virginia made their way north to Ohio cities such as Akron and Cleveland, while in the northern and eastern parts of the state the Baltimore & Ohio Railroad led many migrants to Baltimore or Washington. Wartime recruiters sent special trains to central West Virginia to procure workers for shipyards, defense plants, and government offices in Virginia and Maryland, while the "hillbilly highways" of the 1950s and 1960s led to industrial cities in the Midwest. Southbound 1980s migrants from southern West Virginia clustered sharply in North Carolina counties adjacent to Interstate 77. Clustering was less pronounced at greater distances, however. Census data for 1990, for example, cannot distinguish the residential patterns of West Virginia migrants to Florida from those of migrants from other states.

West Virginia's population rose by 3.3 percent from 1990 to 2010, but at a growth rate well below the national rate of 24.1 percent. Between 2010 and 2020, it decreased by 3.2 percent, compared to the nation, which grew by 7.4 percent. West Virginia, Illinois, and Mississippi were the only states with a net population loss during that decade. Moreover, the population of West Virginians under age 18 fell nearly seven percent between 2010 and 2020. The U.S. Census Bureau estimates that West Virginia has lost an additional 27,609 people (a 1.5% decline) since the 2020 census.

Migrants were typically young people in their prime working years. Their leave taking was usually a rational decision, though often emotional and painful. One national study shows that within a generation, White migrants from West Virginia and other upper south states were as prosperous as other White residents of midwestern and western states. Black West Virginians, who migrated in larger proportions than did Whites, did not fare as well, due to racial barriers that persisted nationally. Anecdotal evidence suggests that women adjusted to the stresses of migration more readily than men, and that many of the classic patterns observed among foreign immigrants also prevailed among Appalachian migrants—chain migration, for example, the process by which migrants from a single family or locality established beachheads in a distant location and then clustered there as more and more members of the chain left home. However, except for aggregate population and economic studies, the phenomenon of migration as it affected individuals and localities has not been examined closely. Thus, until the social, cultural, and individual impact of migration at both the point of origin and destination is studied more intensively, we cannot be certain how well anecdotal evidence reflects the general migration experience.