According to the 40 Mile Point Lighthouse Preservation Society, the lighthouse is located on the shores of Lake Huron in Presque Isle County’s Lighthouse Park (about 7 miles north of Rogers City).
In 1889, the Lighthouse Board recommended that $25,000 be appropriated for construction of a new light and fog signal near Hammond Bay on Lake Huron … Major Milton B. Adams, Eleventh District Engineer selected and surveyed a site approximately 40 miles southeast of Old Mackinaw Point and 40 miles northwest of Thunder Bay.
The main lighthouse structure models the Big Bay lighthouse which was being constructed simultaneously near Marquette in the Upper Peninsula. 40 Mile Point is a two-story duplex with a tower incorporated into the center of the side-wall facing Lake Huron. Its footprint measures 35 feet by 57 feet.
Lighthouse photographer Terry Pepper has some great historical information (and photos) about Forty Mile Point Lighthouse in his Seeing the Light.
As a side note, I had to search to find this photo again and the photos Flickr pulled up for a “40 mile point” search are really cool!