The river is divided into ranges which are nothing more than sections of channel between turns.
5/8ths of a mile from this light, at the edge of the river, stands the Tinicum Front Range Station. By lining up the taller rear lighthouse with the shorter Front Range Station, the Captain or Pilot knew his ship was in the channel. When he got to a point where the Front Range Station and Rear Range lighthouse for the Fort Mifflin Bar Cut Range were lined up he would turn and follow those lights through the Mifflin range.
Since shipping channels have a nasty habit of moving, the Front Range Station has been relocated a number of times over the years.
