Minots Ledge Light

First iron lighthouse on Minots Ledge, 1851

Boston Public Library

Quick Facts

Location:

South of Boston Harbor

OPEN TO PUBLIC:

No

Minots Ledge Light, just south of Boston Harbor, sits near the Cohasset Rocks about a mile off the coast of Cohasset and Scituate.

In 1838, the Boston Marine Society formed a committee to study the feasibility of a lighthouse in the hazardous location. Indeed practical, the Society repeatedly petitioned Congress to get the lighthouse built. Congress ultimately appropriated the funds in 1847 for its construction. 

They chose a rock known as Outer Minot for the site of the lighthouse. This 25-foot-wide stretch of rock only became exposed at low tide on calm days. Putting a lighthouse there would have made it the first in the country in a wave-washed location. However, the lighthouse designer, Captain William H. Swift of the War Department’s Topographical Engineers, believed a stone tower could not be built on Outer Minot. As a result, he designed a 70-foot-tall tower on nine iron pilings cemented into five-foot-deep holes drilled into the stretch of rock. Additionally, he built the keeper’s house and lantern on top of these pilings. The entire structure proved to be far less expensive than a stone tower.¹ 

The iron lighthouse on Minots Ledge went into operation on January 1, 1850. In storms, the structure reportedly swayed as much as two feet in either direction. The first keeper thought the structure so unsafe he quit after 10 months, and the second keeper also expressed grave reservations about its safety. Then, on April 17, 1851, a huge storm completely destroyed the tower, killing the two assistant keepers who were staffing it at the time. All that was left the next morning were a few bent pilings sticking out of the rock.²

While the construction of a new lighthouse took place, a temporary lightship anchored off Minots Ledge marked the hazardous location from 1851 to 1860. Under the US Lighthouse Board, General Joseph G. Totten of the Army Corps of Engineers designed the new Minots Ledge Light, with modifications by Captain Barton S. Alexander. Totten and Alexander intended the tower to be built of interlocking granite blocks, each anchored to those above and below with massive iron dowels. Construction began in July 1855. First, they leveled the ledge to accommodate the seven huge granite blocks that formed the foundation. Because construction could only be done at low tide on calm days, workers cut and assembled the stones on Government Island in Cohasset Harbor. They notched each stone to fit the adjacent ones and erected the tower on shore.³ 

Then, workers dismantled the tower and hauled the stones by oxen to a vessel that transported them to the ledge across the water. They laid the first granite block on the ledge in July 1857, the cornerstone in October 1858, and the final stone in June 1860. The stones created an 89-foot tower, the first 40 feet of which was solid with the exception of a central cistern. A hollow tower containing a storeroom, workspace, and living quarters topped the base. A bronze lantern surmounted the top, its rooftop finial about 108-feet above the base of the tower. The lighthouse went into operation on November 15, 1860, following the installation of a second-order Fresnel lens in the lantern.⁴ 

In 1894, Minots Ledge Light received an update to its lens. The installation of a rotating mechanism for the Fresnel Lens made it a flashing light. Someone decided the flash of 1-4-3 stood for “I Love You.” Minots Ledge Light, as a result, received the nickname “I Love You Light.” 

In 1947, the US Coast Guard automated the light by powering it with batteries. An underwater cable was installed in 1964 and at that time the second-order Fresnel lens replaced with a third-order lens. When the cable was damaged in a storm in 1971, the light was again powered by batteries until converted to solar power in 1983.⁵

Prepared by Nancy S. Seasholes, 2009. Updated 2025.  

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Footnotes

1. Jeremy D'Entremont,  "History of Minots Ledge Light, Scituate, Massachusetts," Minots Ledge Light history - NEW ENGLAND LIGHTHOUSES: A VIRTUAL GUIDE, accessed November 17, 2025;  Dudley Witney, The Lighthouse, (Boston: New York Graphic Society, 1975), 44.
2. Jeremy D'Entremont,  "History of Minots Ledge Light, Scituate, Massachusetts," Minots Ledge Light history - NEW ENGLAND LIGHTHOUSES: A VIRTUAL GUIDE, accessed November 17, 2025.
3. Jeremy D'Entremont,  "History of Minots Ledge Light, Scituate, Massachusetts," Minots Ledge Light history - NEW ENGLAND LIGHTHOUSES: A VIRTUAL GUIDE, accessed November 17, 2025;  Dudley Witney, The Lighthouse, (Boston: New York Graphic Society, 1975), 44-45.
4. Ibid.
5. Jeremy D'Entremont,  "History of Minots Ledge Light, Scituate, Massachusetts," Minots Ledge Light history - NEW ENGLAND LIGHTHOUSES: A VIRTUAL GUIDE, accessed November 17, 2025; Lighthouse Friends, "Minot's Ledge Lighthouse," Minot’s Ledge Lighthouse, Massachusetts at Lighthousefriends.com, accessed November 17, 2025.