Marker is at the intersection of West Virginia Route 9 and Sir John Run Road, Morgan County WV, on the right when traveling west on State Route 9.
Sir Johns Run formerly served on the old Baltimore and Ohio Railroad mainline as an early passenger station for Berkeley Springs. Today it is primarily a residential community of Berkeley Springs accessible by Sir Johns Run Road (County Route 3). Sir Johns Run had its own post office in operation from 1850 to 1938. Today, the stream and its namesake hamlet are a site on the Washington Heritage Trail.