Cross Brook is a tributary of the Six Mile Run, a stream that drains sections in Somerset and Middlesex Counties, New Jersey in the United States. It is a relatively small stream.Its source is near Suydam Road in eastern Franklin Park. It flows through the Six Mile Run Reservoir Site and crosses Jacques Lane. After Jacques Lane it drains into the Six Mile Run.Cross Brook is a slow-moving stream, although it is not marshy. Some species of fish may be expected to be found in it.Cross Brook is a short stream, only crossing one road. There are a few trails in the woods that lead to it.