Congress originally appropriated $50,000 in 1878 for a lighthouse atop Tillamook Head, the 1,200-foot promontory visible from Seaside. A survey quickly revealed the problem: the headland was so tall that fog would swallow any light placed on its summit. The alternative was worse in every practical sense but better for navigation -- a jagged basalt rock sitting in open ocean, barely an acre in size, fully exposed to the Pacific. H. S. Wheeler led the survey aboard the cutter Thomas Corwin in 1879, and the U.S. Army Corps of Engineers began construction under George Lewis Gillespie Jr. The final cost reached $125,000, more than double the original appropriation. The light's beam could reach ships eighteen miles out, and a steam foghorn warned them when the beam could not.

Four keepers staffed Tillamook Rock Light at any given time, isolated on their acre of basalt with nothing between them and the storms rolling in from the Pacific. Over the decades, waves shattered the lens, damaged the structure, and eroded the rock itself. Repairs cost $12,000 and were not fully completed until February 1935 -- more than fifty years after the light first shone. The keepers' commute was a journey by boat through unpredictable surf, or later, by helicopter when weather permitted. The lighthouse operated for seventy-six years before being decommissioned in 1957, replaced by more modern navigation aids that did not require people to live on an exposed rock in the open ocean.

After decommissioning, Terrible Tilly passed through the hands of several private owners, each inheriting a structure that the sea was steadily reclaiming. In the 1980s, a company called Eternity at Sea converted the lighthouse into a columbarium -- a repository for cremated remains. For nearly two decades, urns were placed inside the battered walls where keepers had once maintained their vigil. The columbarium operation ended in 1999, but the ashes remain. In 2022, the property was listed for sale again, its buildings in need of complete renovation after decades of damage from storms, nesting seabirds, and sea lions that have claimed the rock's lower surfaces. Access is limited to helicopter only, and even the owners cannot visit during nesting season.

Tillamook Rock Light was added to the National Register of Historic Places in 1981, exactly one hundred years after its first beam swept the ocean. It is part of the Oregon Islands National Wildlife Refuge, which means the seabirds that nest on its surfaces have more legal protection than the building itself. The lighthouse remains visible from Seaside, Cannon Beach, and the trails of Ecola State Park -- a dark shape on the horizon that looks, from a distance, like it could be a natural feature of the rock rather than something humans once spent 500 days and a fortune constructing. That illusion is fitting. Terrible Tilly has always been more rock than lighthouse, more nature than engineering. The Pacific built it, in a geological sense, and the Pacific is slowly taking it back.