2018 U.S. news in pictures from A to Z

People stand behind the border fence that divides the United States and Mexico in San Diego, California, the United States, on Nov. 17, 2018. Officers of the U.S. Customs and Border Protection (CBP) have tightened preparations at the U.S.-Mexico border in San Diego, California, for the arrival of massive caravans of Central American migrants. (Xinhua/Zhao Hanrong)