More than 600 marches could draw hundreds of thousands of people across the country, from immigrant-friendly cities like Los Angeles and New York City -- where a march has started -- to conservative Appalachia and Wyoming under the banner Families Belong Together. Though many who show up will be seasoned anti-Trump demonstrators, others will be new to immigration activism, including parents who say they feel compelled to show up after heart-wrenching accounts of children forcibly taken from their families as they crossed the border illegally.