California is the most populous state of the United States, located on its West Coast.
Teenage Mutant Ninja Turtles appearances
The Ninja Turtles visit both the California Redwoods and San Francisco in the 1990 video game World Tour.
In both the Mirage continuity and in the 2003 TV series stories, April O'Neil's sister Robyn lives in Los Angeles, the state's most populous city.
In the Fox Trap story of the Teenage Mutant Ninja Turtles Adventures comics, Raphael, Ninjara and Naga all travel there.
The three-part storyline where the Ninja Turtles face Kurko in Las Tortugas Ninja takes place at and under Mount Shasta, a volcanic mountain in northern California.
The IDW continuity miniseries Casey & April takes places mostly in California's Mojave Desert, where Aka's trailer is located.