California is one of the fifty states that compose the United States of America. Notable cities in California include Los Angeles, San Diego, and San Francisco. Smaller settlements include Pismo Beach and Cooper's Mill.
A Cybertronian incident in California (very likely the one above) was witnessed by Ruan Sablik.
When Rom arrived on Earth in 2016, he landed just outside of the Californian town of Pismo Beach. His initial encounters with the Dire Wraiths all took place within Northern California before he left for Seattle.
His comrades Orphion and Livia, retracing his steps, landed in Pismo Beach not far from Rom's own landing site. After Baron Karza's defeat, Rom returned to California to check up on Camilla Byers before reuniting with Orphion and Livia. The Space Knights soon left California to travel to sites of unusual Wraith activity.