A day laborer waits for employers in San Diego, the United States, Jan. 5, 2019. Statistics show that the so-called "illegal immigrants" have contributed a lot to the U.S. economy. A cross-section of Californian leaders in business, education, law enforcement and religion testified at the Supreme Court of the United States in 2016 that a quarter of illegal immigrants in the country lived in California, which accounted for 7 percent of the Californian population. (Xinhua/Li Ying)