In 1790, the year of the first U.S. Census, the population of the territory which is now West Virginia was 55,873. The nation's population in that first census was 3,929,214. West Virginia's population grew from 1790 until the 1950s, peaking according to the 1950 Census at 2,005,552. According to the 2020 census, there were 1,793,716 West Virginia residents, a decline of nearly 60,000 since 2010. West Virginia was one of only three states (with Illinois and Mississippi) to lose population during that decade. The U.S. Census Bureau estimates that West Virginia has lost an additional 27,609 people since the 2020 census.

West Virginia's share of the U.S. population fell from 1.4 percent in 1790 to 0.54 percent in 2020. This implies that the state's population growth has fallen well short of national growth since the first census was taken in 1790. This is true in general but not true for every part of that long period of time. From 1900 to 1950, West Virginia's population exceeded national growth as the state’s expanding mining and manufacturing industries boosted economic growth. However, the strong population gains registered during the first half of the 20th century have not been repeated consistently since.

After reaching a high of just over two million in 1950, the number of West Virginians has risen and fallen with the state's economy but declined overall. With increasing mechanization in the coal mines and good economic opportunities in other parts of the country, West Virginia’s population dropped by 261,000 residents from 1950 to 1970. The energy crises of the 1970s brought a resurgence in coal mining, which contributed to a rebound in the state's population to near the 1950 level by the end of the decade. Unfortunately, a global recession during the 1980s, coupled with economic restructuring in the state's major manufacturing and coal mining sectors, pushed the number of residents down to 1,793,477 by 1990. West Virginia's population rose by 3.3 percent from 1990 to 2010, 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.

The reasons behind the recent stagnation in West Virginia population growth are related to the state's demographic structure. Population change depends primarily on two factors: natural increase and net migration. Natural increase is the annual difference between births and deaths. Since the state’s number of births since 1990 have been very close to its number of deaths, West Virginia's population has gotten little boost from natural increase. This means that state population growth has been dependent on net migration, which is the difference between the number of residents moving into versus leaving the state. Due to the state's sluggish economic growth, West Virginia has had trouble attracting more migrants than it loses to other states, and in some years, net migration has been negative.

West Virginia's population levels have always differed significantly in various counties. In 1900, Kanawha County, with the largest population in the state, had 54,696 residents, compared to Hancock County with 6,693 residents. However, since then, the population gap between larger and smaller counties has risen dramatically. The largest county in 2020 was again Kanawha County, with 180,745 residents, compared to Wirt County with 5,194 residents.

County population growth tends to follow regional economic performance. None of the major southern coal-producing counties, Boone, Logan, McDowell, Mingo, Raleigh, or Wyoming ranked in the top 10 in population size in 1900. With the expansion of the coal industry during the first half of the century, McDowell, Raleigh, and Logan counties all ranked in the top 10 in 1950. But due to changes in the coal industry and the lack of diversification in these counties' economies, only Raleigh remained in the top 10 in 2020 (it was sixth). The experience of McDowell County dramatically illustrates the changing fortunes of the coal industry on population size. In 1900, the Census Bureau counted 18,747 residents in McDowell County. By 1950 that number had swelled to 98,887 residents, while the 2010 Census found just 19,111 McDowell residents, a decline of 30 percent from 2000; by 2020, McDowell's population had dropped to 16,916.

Overall population growth during the post-World War II period has favored counties with larger cities and the "bedroom" counties from which cities draw commuters. By far the fastest-growing parts of the state since 1950 have been the three counties in the Eastern Panhandle (Morgan, Berkeley, and Jefferson) and Putnam County. These four counties have benefited from the expansion of nearby metropolitan areas. Berkeley and Jefferson are now classified as part of the Washington Primary Metropolitan Statistical Area, while Putnam County is now part of the Charleston Metropolitan Statistical Area. During the 2010s, Berkeley, Monongalia, and Jefferson counties grew the fastest: Berkeley by 17,907 (17.2 percent), Monongalia by 9,633 (10.0 percent), and Jefferson by 4,203 (+7.9 percent). Counties with the largest population decreases were Pendleton (-20.2 percent), Ritchie (-19.2 percent), and Calhoun (-18.3 percent).

Counties registering the largest population losses since 1950 have been the coal-dependent counties, particularly in the southern part of the state, and the manufacturing counties in the Northern Panhandle.

Population change has also had an impact on West Virginia's cities. In 1900, the largest city in the state was Wheeling, with a population of 38,878, followed by Huntington, Parkersburg, Charleston, and Martinsburg. By 2020, the top five cities were Charleston, with 48,864 residents, Huntington, Morgantown, Parkersburg, and Wheeling. In addition, during the 21st century, West Virginia's incorporated places collectively have lost population, in contrast to population gains registered by the state's unincorporated areas.

West Virginia remains a rural state with mostly small cities. That is increasingly unusual. In 1900, 86.9 percent of West Virginians lived in sparsely populated rural areas, compared to 60.4 percent nationally, but 10 other states in 1900 had larger shares of residents living in rural areas. By 2020, only two other states (Maine and Vermont) were more rural than West Virginia. Most states saw their residents concentrate in urban areas during the 20th century. West Virginia did not participate in this trend, and a large share of residents continue to live in rural areas today.