Before 1700 AD, Yurok people established the village of Tsurai on bluffs overlooking Trinidad Bay.
 The first European sighting of Trinidad Harbor was by the Manila galleon captain Sebastian Rodriguez Cermeño, who did not make landfall.
The next visit was by Bruno de Heceta and Juan Francisco de la Bodega y Quadra
of the Spanish Navy.
Their two ships anchored in Trinidad Bay on June 9, 1775.
On 11 June, which was Trinity Sunday, a formal act of possession was conducted.
At the place where a wooden cross was erected stands a carved stone cross bearing the inscription.
Carolus III Dei G. Hyspaniorum Rex.,
in the name of King Carlos of Spain.
 The area was named "la Santisima Trinidad".

Settlers arrived on the James R. Whitting in 1850 and founded the town, renamed Warnersville in honor of R.V. Warner, one of the settlers.
The first post office opened in Trinidad in 1851.

Trinidad was the original county seat of the eponymous Trinity County from 1850 to 1851, and of Klamath County, one of California's original counties, from 1851 to 1854.
At that time Trinidad became part of the newly created Humboldt County after its creation in 1853, with its county seat in Eureka.
Klamath County was finally dissolved in 1874.

During the American Civil War, from July to October 1863, California volunteers fighting the local Indians in the Bald Hills War were stationed in the town, in Trinidad Camp, to protect it and the coast road from Indian raids, until they were moved four miles north to Camp Gilmore.
Trinidad was incorporated in 1870 as a City of the State of California, USA.

Trinidad resident Henry A. Boyes was a first sergeant with the 5th Marines in World War II; his service was described by Eugene Sledge in the book, With the Old Breed: At Peleliu and Okinawa.
Before 1700 AD, Yurok people established the village of Tsurai on bluffs overlooking Trinidad Bay.  The first European sighting of Trinidad Harbor was by the Manila galleon captain Sebastian Rodriguez Cermeño, who did not make landfall. The next visit was by Bruno de Heceta and Juan Francisco de la Bodega y Quadra
of the Spanish Navy. Their two ships anchored in Trinidad Bay on June 9, 1775. On 11 June, which was Trinity Sunday, a formal act of possession was conducted. At the place where a wooden cross was erected stands a carved stone cross bearing the inscription. Carolus III Dei G. Hyspaniorum Rex., in the name of King Carlos of Spain.  The area was named "la Santisima Trinidad".
Settlers arrived on the James R. Whitting in 1850 and founded the town, renamed Warnersville in honor of R.V. Warner, one of the settlers. The first post office opened in Trinidad in 1851.
Trinidad was the original county seat of the eponymous Trinity County from 1850 to 1851, and of Klamath County, one of California's original counties, from 1851 to 1854. At that time Trinidad became part of the newly created Humboldt County after its creation in 1853, with its county seat in Eureka. Klamath County was finally dissolved in 1874.
During the American Civil War, from July to October 1863, California volunteers fighting the local Indians in the Bald Hills War were stationed in the town, in Trinidad Camp, to protect it and the coast road from Indian raids, until they were moved four miles north to Camp Gilmore. Trinidad was incorporated in 1870 as a City of the State of California, USA.
Trinidad resident Henry A. Boyes was a first sergeant with the 5th Marines in World War II; his service was described by Eugene Sledge in the book, With the Old Breed: At Peleliu and Okinawa.
Trinidad, California