Worldwide attention to environmental issues led to the first Earth Day in 1970. Container Corporation of America, a large producer of recycled paperboard, sponsored a contest for art and design students at high schools and colleges across the country to raise awareness of environmental issues. It was won by Gary Anderson, then a 23-year-old college student at the University of Southern California, whose entry was the image now known as the universal recycling symbol. The symbol is not trademarked and is in the public domain. The public-domain status of the symbol has been challenged, but this challenge was unsuccessful owing to the wide use of the symbol. However, the universal symbol may have been inspired by similar existing recycling symbols, such as one featuring two arrows chasing each other in a circle that Volkswagen stamped in the early 1960s into some automobile parts it remanufactured.