Preparation for construction of the Grassy Island Range Light Towers began in 1866 but due to complications with dredging, the structures were not completed until 1872. The structures were white wooden towers with sixth-order Fresnel lenses. The front tower was 27 feet from base to ventilator ball and the rear or upper tower was seven feet taller, with just over 676 feet distance between the two towers.
A keeper’s dwelling was built between the lights. Due to a widening of the channel through Grassy Island in 1966, the light towers were relocated to the Green Bay Yacht Club’s property at the east entrance to the Fox River.
They were relocated again to the breakwall on the west side of the harbor in 1998. The lights were placed on the Wisconsin Registry of Historic Places in 2004 and on the National Register of Historic Places in 2005.