The American Public Health Association (APHA) is Washington, D.C.-based professional organization for public health professionals in the United States. Founded in 1872 by Dr. Stephen Smith, APHA has more than 30,000 members worldwide. The Association defines itself as being "the oldest and most diverse organization of public health professionals in the world." It defines its mission as: "The Association aims to protect all Americans and their communities from preventable, serious health threats and strives to assure that community-based health promotion and disease prevention activities and preventative health services are universally accessible in the United States.