Impact of Homeland Security The advent and rapid growth of the national homeland security program since the beginning of the 21st century has brought major changes—political, social, and economic—to the United States. Major legislation and executive orders early in the first term of President George W. Bush resulted in the most significant reorganization of the federal government since the National Security Act of 1947, including the merger of 22 legacy agencies into a new, single Department of Homeland Security. Hundreds of billions of dollars in federal homeland security grants have been passed through to state and local governments. The modern threat of terrorism and the new emphasis on community and citizen preparedness and resiliency are reminiscent of civil defense measures or programs implemented in response to the threat of nuclear attack during the Cold War.