In the late 1700s and early 1800s, salt furnaces in Kanawha County were initially fueled by timber, but as the forests became depleted, operators started mining coal. By 1840, 90 furnaces used 200,000 tons of coal a year to make salt. Over 900 workers, many enslaved, mined the coal. Even after the salt industry declined, coal was still needed for things like coal oil and fueling steamboats. By 1860, 25 coal companies employed more than 1,000 people.