Migrants, part of a caravan of thousands from Central America trying to reach the United States, climb a border fence as they try to cross illegally from Mexico to the U.S, in Tijuana, Mexico, December 3, 2018. Reuters photographer Alkis Konstantinidis: "In this picture, the immensity of the wall as well as the second fence behind it set the scene. For me, it is the tension on the woman's face which dominates the frame and sums up a feeling of uncertainty, of not knowing what lies beyond the wall." REUTERS/Alkis Konstantinidis SEARCH "IMMIGRATION POY" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2018 PACKAGES. TPX IMAGES OF THE DAY.