Black Vermillion River, a stream of northeastern Kansas, also called the Black river, consists of two forks. The north fork rises in Marshall county, near the northeast corner, and flows south; the south fork rises in the southern part of Nemaha county and flows northwest, the two forming a junction near the little village of Vliets. From this point the main stream follows a southwesterly course until it empties into the Big Blue river near the southern boundary of Marshall county.