Six Mile Run is a tributary of the Millstone River that drains a large area in central Franklin Township in Somerset County and as well western portions of North Brunswick and South Brunswick Townships in Middlesex County, New Jersey in the United States.

27) left the Raritan River at New Brunswick to the point the roadway crossed the stream.

It then joins with the Nine Mile Run, a major tributary, and crosses South Middlebush Rd.

Six Mile Run is easily accessible in several places, including Cozzens Lane and the residential development.

Many large fish are found in the deep pools near the Delaware and Raritan Canal.