The unmanned reef lights of the Florida Keys were erected between 1921 and 1935. As they were marking local hazards, they did not need to be visible for as far as the reef lights that were erected during the 19th century. By the time these lights were erected, older lighthouses were being automated, and these new lights were designed to be automated from the start. The lights resembled the older reef lights in having a skeletal pyramidal upper structure on screw-pile foundations.