Split Rock Lighthouse

North of Two Harbors, Minnesota, USA

Lake Superior

This is the famous Split Rock Lighthouse on the Western shore of Lake Superior north of Duluth, Minnesota. It is the highest lighthouse in the United States, built on 7.63 acres of land that cost the U.S. Government just $200.00. It was built to help captains overcome two main hazards. First, the large iron ore deposits in the area threw off their magnetic compasses, making navigation difficult. Second, this lighthouse is built at the top of a 130-foot high cliff. The water is very deep in front of this light, and it was hard to get good soundings as a result. This led to several ships crashing into the face of the cliff in the fog. The complex was built for $72,000 and opened in 1910. Split Rock also featured a steam-powered fog signal.

When Split Rock was built, all constuction equipment and materials had to be brought in by ship and lifted up the cliff using a 6-ton, cast-iron steam-powered derrick, which was erected in May, 1909 and used until 1916 to hoist supplies (and people!). Over 310 tons of building materials were eventually lifted.

Situated along the "International Highway" between Duluth, Minnesota and Thunder Bay, Ontario, Split Rock once had three lighthouse keepers: a head keeper and two assistants. Until 1931, they staffed the facility seasonally.

The physical plant consisted of the main light tower, fog signal building, oil storage building, three barns, and two-story brick residences to house the three keepers.

In 1969, Split Rock was declared obsolete by the Coast Guard and decommissioned. Since 1971, the Minnesota Historical Society has operated the facility as a museum. Located in a state park, it is open daily from May through October.

As early as the 1930s, Split Rock was a popular tourist attraction. Access was simplified in 1935 when the Civilian Conservation Corps built a road leading to the lighthouse. By 1939, the Coast Guard stated that Split Rock was "probably the most-visited lighthouse in the United States." In 1941, a snack bar and gift shop opened to serve visitors.

For information on visiting this light, which is located 20 miles north of Two Harbors, MN, call (218) 226-6372.

Split Rock once had a Second Order lens and IOV lamp rated at 1.2 million candlepower. It now features a third order Fresnel lens rated at 370,000 candlepower, although it was once rated at 450,000 candlepower. It is now officially rated at 22 miles visible range.

Although this light source is no longer used, it is ceremonially lit once a year on the weekend nearest to November 10th, to commemorate the sinking of the Great Lakes ore frighter Edmund Fitzgerald. This ship broke up on November 10th, 1975 near Whitefish Point in Lake Superior during an intense gale. She was lost with all hands; no bodies were ever recovered.

The lens assembly shown above is seven feet across, consists of 254 cut glass prisms, weighs 4½ tons, and is rotated by a clockworks mechanism driven by a 250 lb. weight. The light source was a incandescent oil vapor (IOV) lamp until 1940, when a 1000 watt electric lamp was installed, following wiring of the station in 1939. Although the tower is only 54 feet tall, the height of the cliff places the focal plane of the light source 168 feet above mean lake level.

This powerful beacon flashed every 10 seconds for almost 60 years, but it is now lit only on special occasions.

Split Rock Lighthouse features a compressed-air fog signal housed in a separate building 50 feet east of the tower. The twin horns point eastward toward Lake Superior. During operation, the fog signal emits a two-tone ("beeeeeeee-ohhh!) blast that lasts for two seconds. After 18 seconds of silence, the blast repeats.

The signal was originally steam-powered, but now twin gasoline-powered air compressors now power the signal. The original engines were replaced in 1932 and finally removed in 1961.