| Six Mile Run | |
| Image Alt: | Six Mile Run near canal |
| Map: | Six Mile Run.JPG |
| Source1 Coordinates: | 40.4597°N -74.4864°W |
| Mouth Coordinates: | 40.4725°N -74.5722°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Progression: | Millstone River, Raritan River, Atlantic Ocean |
| Source1 Elevation: | 39feet |
| Tributaries Left: | Steep Hill Brook, Middlebush Brook |
| Tributaries Right: | Cross Brook, Nine Mile Run |
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.
Six Mile Run derives its name (along with other area streams including Mile Run, Three Mile Run, Nine Mile Run, and Ten Mile Run) from the distance early surveyors estimated it was from the point where the historic King's Highway (now Rt. 27) left the Raritan River at New Brunswick to the point the roadway crossed the stream. The estimates were not very accurate but the stream names have remained in use ever since.
Six Mile Run starts near Corporate Road in North Brunswick 40.4597°N -74.4864°W. It crosses Cozzens Lane, then flows through a residential development. It joins up with the drainage from a lake then crosses Rt. 27. It then joins with the Nine Mile Run, a major tributary, and crosses South Middlebush Rd. It then crosses Canal Road and drains into the Millstone River 40.4725°N -74.5722°W.
Six Mile Run is easily accessible in several places, including Cozzens Lane and the residential development. It also can be accessed at Route 27, South Middlebush Road, and Canal Road, as well as the D&R Canal Trail. It can be also accessed by trails in the Six Mile Run Reservoir Site.
Six Mile Run is generally between rocky and muddy terrain. Near Cozzens Lane, the streambed is rocky with a muddy covering. It is quite deep in many places. Farther downstream in the residential development, the stream becomes more rocky and fast flowing. It then becomes rocky and deep near Route 27, and remains like that for most of its downstream course. It widens considerably when it joins the Nine Mile Run. Near its mouth, it has a mixture of pebbles and sand for its streambed. Many large fish are found in the deep pools near the Delaware and Raritan Canal.
The Six Mile Run has a large unnamed tributary that flows northward, crossing Skillmans Lane, Bennets Lane, and Veronica Avenue.