Mitchell completed a geographical survey of North Carolina in 1828 and observed a peak in the Black Mountains he believed to be higher than Grandfather Mountain, at that time thought to be the highest in the region. In 1835, he first measured the height of this mountain, at the time known as Black Dome. Through subsequent measurements in 1838 and 1844, Mitchell proved it was higher than New Hampshire's Mount Washington, establishing the peak as the highest above sea level in the Eastern US.