Three most significant federal health agencies are:

1. Centers for Disease Control and Prevention (CDC)
2. Food and Drug Administration (FDA)
3. Agency for Healthcare Research and Quality (AHRQ) 

Another important ancient Greek concept that influenced the formation of the United States government was the written constitution. The original U.S. voting system had some similarities with that of Athens. In Athens, every citizen could speak his mind and vote at a large assembly that met to create laws.