A panoramic view of Signal Hill in 1923, a small city in Southern California. On June 21, 1921, oil was discovered in Signal Hill, part of the Long Beach Oil Field, and the city was soon covered with over 100 oil derricks (seen here). Because of its prickly appearance at a distance, it gained the nickname "Porcupine Hill". Today, most of the oil wells and nodding donkey oil pumps are gone. Signal Hill is now a mix of residential and commercial areas.Photo: The Aerograph Co.; Restoration: Jujutacular