Mendocino County was one of the original counties of California, created in 1850 at the time of statehood.

The county derives its name from Cape Mendocino (most of which is actually located in adjacent Humboldt County), which was probably named in honor of either Antonio de Mendoza, Viceroy of New Spain, 1535–1542 (who sent the Juan Rodríguez Cabrillo Expedition to this coast in 1542), or Lorenzo Suárez de Mendoza, Viceroy from 1580 to 1583. Mendocino is the adjectival form of the family name of Mendoza.

Neither Spanish nor Mexican influence extended into Mendocino County beyond establishing two Mexican land grants in southern Mendocino County: Rancho Sanel in Hopland, in 1844 and Rancho Yokaya that forms the majority of the Ukiah Valley, in 1845.

Establishment of the Round Valley Indian Reservation in March 30, 1870, did not prevent the segregation that continued well into the 20th century. Other tribes from the Sierra Nevada mountains were also located to the Round Valley Indian Reservation during the “California Trail Of Tears”, where the Natives were forced to march in bad conditions to their new home in Round Valley.

NameNational LandmarkState LandmarkPoint of InterestOther Designation
Frog Woman RockN/A549N/AN/A
Fort BraggN/A615N/AN/A
Round ValleyN/A674N/AN/A
Mendocino Presbyterian ChurchN/A714N/AN/A
Sun HouseN/A926N/AN/A
Temple Kwan TaiN/A927N/AN/A
Ukiah Vichy Springs ResortN/A980N/AN/A
Point Arena Light Station900021891035N/AN/A
Glass BeachN/AN/APoint of InterestState Park