When the Clean Air Act Amendments of 1990 passed, lawmakers were more concerned about smog and acid rain than greenhouse gas emissions. The acidic droplets were even damaging the stone on Washington, D.C.'s monuments, including the U.S. Capitol itself. As a result, Congress acted with near unanimity. When a final bill came for a vote, 89 senators supported it. In the House, the vote was 401-25. It was the first major rewrite of the nation's air laws since the 1970s. The debate and votes surrounding the amendments, which gave the federal government more authority to control air pollution, are a stark contrast to the ongoing sharp divisions over dealing with global warming.