Due mostly to a decline in employment in the coal mining industry, McDowell County's population has decreased from almost 100,000 in 1950 to less than 20,000 in 2020.

The people of McDowell County suffer high rates of drug abuse and poverty, and have a life expectancy well below the national average.

[5] In 1861, as the nation lurched toward civil war, delegates from McDowell County voted in favor of Virginia's secession from the United States.

[4] However, in 1866 the state legislature relocated the county seat to a farm near the mouth of Mill Creek.

[5] In 1863, West Virginia's counties were divided into civil townships, with the intention of encouraging local government.

[8] McDowell County was divided into three districts: Big Creek, Elkhorn, and Sandy River.

However, in the next few decades major breakthroughs in mechanization in the coal industry resulted in job declines.

[12] While running for president, John F. Kennedy visited McDowell County and promised to send help if elected.

The highest elevation in the county is approximately 1,036 m (3,399 ft) on the northwest slope of Flat Top Mountain.

[25] The largest ancestry groups were: 13.7% Irish, 12.0% German, 11.5% English, 8.0% American, 2.8% Sub-Saharan African, 2.7% Italian, 2.0% Dutch, and 1.1% Scotch-Irish.

High rates of smoking and obesity and a low level of physical activity appear to be contributing factors to the declining life expectancy for both sexes.

[35] At the height of the scandal, executives buried large volumes of documents in a trench in an attempt to conceal the fraud from the bank's accounting firm and from the Office of the Comptroller of the Currency.

[39] The power of industrial and mining political systems turned the county towards the Republican Party between 1890 and 1932, even supporting William Howard Taft during the divided 1912 presidential election.

Since 1996, the county has trended Republican again, due to the prevailing environmentalist stances in the Democratic Party regarded as hostile towards coal mining interests.

A mixed use, multistory building in Welch aimed at reducing the housing shortage for teachers opened in 2022.

[46][47] Melville Davisson Post used McDowell County as the setting of his short story "Once In Jeopardy".

This 1890s tale of the working out of a legal problem is rich in description of the people, customs, politics, and recent history of the area, including the impact of the railroad coming through and the rise of Republican influence.

[48] Author and NASA engineer Homer Hickam grew up in Coalwood, McDowell County.

His memoir October Sky, which was adapted into a 1999 Hollywood film, is based on his childhood amateur rocket building experiences in Coalwood.