Waving blue campaign signs and cheering their support, thousands of people gathered to hear Sen. Barack Obama on Friday evening as the Democratic White House hopeful made his first presidential campaign visit to South Carolina. Obama was keenly aware of the significance of appearing before a crowd in Columbia just a few days after a black South Carolina legislator said if Obama won the nomination, it would lead to losses for Democrats in Congress and governorships. "Everybody's entitled to their opinion," Obama said. "But I know this - that when folks were saying we're going to march for our freedom, somebody said we can't do that."And when others said blacks couldn't sit at lunch counters, blacks did that, said Obama, who ended his thought with: "Yes, we can." The crowd then started chanting the line. Obama also touched on the diversity of the nearly 3,000 people at the event, saying a generation ago, blacks were harassed if they walked across the Statehouse grounds a few blocks away. "Twenty years ago, nobody would have believed this crowd right here in South Carolina," Obama said.