Wayland Town Crier 4/16/10: 'Wayland A to Z': 'S' is for 'Sudbury River'. The Sudbury River wends its way from Cedar Swamp in Westborough through Framingham, Wayland and Concord, where it merges with the Assabet to become the famed Concord River. Such historic fame does not attach to the Sudbury, which may be the slowest river in the nation! As the often threadlike river traverses the length of Wayland, south to north, so too its languor has influenced Wayland’s evolution from its agricultural beginnings to the residential town it has become.