What river flows through Arkham in Lovecraft's stories?

The river flowing through Arkham in Lovecraft's stories is the fictional Miskatonic River. It is one of the central geographic features of Lovecraft's imagined New England and gives its name to both Miskatonic University and the surrounding region.

Arkham is portrayed as a Massachusetts city in the Miskatonic River Valley. The river links several important locations in Lovecraft Country: its headwaters are associated with Dunwich, while it eventually reaches the Atlantic near Arkham, Kingsport, and Martin's Beach. This shared landscape helps make the stories feel like parts of one connected world.

The Miskatonic is not a real river. Lovecraft created the name from New England place-name patterns, and one proposed real-world influence is the Housatonic River, which runs through western Massachusetts and Connecticut. Lovecraft himself placed his imaginary river somewhere north of Salem, perhaps near Manchester.

Readers sometimes mistake it for the Charles River because Arkham is imagined in Massachusetts, but the Charles is a real river associated with Boston. Miskatonic River is the canonical answer in Lovecraft's fiction.