They were the fifty-first and fifty-second counties in West Virginia, and only Lincoln, Summers, and Mingo were created after them.

Beginning in 1863, West Virginia's counties were divided into civil townships, with the intention of encouraging local government.

This proved impractical in the heavily rural state, and in 1872 the townships were converted into magisterial districts.

[5] Most of the 47 people killed in the 1985 Election day floods were in Pendleton and Grant counties, according to the National Weather Service.

[6] At Franklin, the Pendleton County seat, the South Branch of the Potomac River crested at 22.6 feet during the incident.

[13] As of the 2010 United States census, there were 11,937 people, 4,941 households, and 3,435 families living in the county.

Grant County lies within West Virginia's 2nd congressional district.

Politically, Grant County was historically a major outlier in West Virginia.

While the rest of the state did not become a Republican bastion until the 21st century after having leaned heavily Democratic between the New Deal and Bill Clinton’s presidency, Grant County has always been among the most strongly Republican counties in the country.

Notably, in 2016, 2020, and 2024, Donald Trump received the highest percentages of the vote ever cast for a presidential candidate in this county.

He held Democratic candidates Hillary Clinton, Joe Biden, and Kamala Harris to 10%, 11%, and 10% of the vote, respectively.

At the state level, Grant County voted for popular Democratic governor Joe Manchin over his GOP opponent Russ Weeks by over 20 points in 2008.

The Delegate for Grant County is John Paul Hott (R) for district 85.

The position of the Grant County Administrator is currently held by Michelle Sites.

The current members of the County Commission are Kevin P. Hagerty, Scotty Miley and Tyson Riggleman.