Gilmer is one of West Virginia's smaller counties being only 342.4 square miles; it is just twenty air-miles from the geographical center of the state. It was created in 1845 after the rural people of present Gilmer and Calhoun Counties wearied of traveling to Weston or Charleston for their court business. It was named for Thomas Walker Gilmer, a son of the Old Dominion who was accidentally killed during the height of his career.

The genealogy of this county is similar to that of a person. Its parent counties were Lewis and Kanawha. It's grandparent counties were Harrison and Boutetourt. It's great-grandparent county was Monongalia. And, before that, it was called West Augusta, Virginia. It even has children, Roane and Calhoun both born in 1856 Lewis and Kanawha. It's grandparent counties were Harrison and Boutetourt. It's great-grandparent county was Monongalia.

Except for the stray trader, hunter, and Indians, Gilmer County was unsettled until 1800 when Jacob Bush came from today's Lewis County, then called Harrison, to settle as a squatter on Cedar Creek about 1.5 miles from the current U.S. Route 33/119. It was six more years before Michael Stump and his sons settled on Steer Creek. In 1810 Peter McCune erected his cabin on the Little Kanawha near the mouth of Leading Creek and became the first settler in DeKalb District. Shortly thereafter, Adam Heckert and his family settled at Troy. Heckert stopped for a short time in present-day Lewis in his journey from Sugar Creek in present day Barbour County. In 1816 William Stalnaker, a Captain in the War of 1812, chose a home site near the mouth of Mill Seat Run on the LK. The first recognized 'town' in Gilmer County was DeKalb, the post office being opened in 1835.

The county is the birthplace of the West Virginia state song, "The West Virginia Hills." This song, like "Country Roads," stirs a tingling in the hearts of all native West Virginians and those who have adopted her as a homeland (yes, even those whose ancestors came from West Virginia.)

The current estimated population of Gilmer County is 7350