January:
- NASA's New Horizons spacecraft launches on a mission to Pluto.
February:
- The Winter Olympics begin in Turin, Italy.
March:
- The controversial book "The Da Vinci Code" by Dan Brown is released.
April:
- The United States Supreme Court strikes down the Partial-Birth Abortion Ban Act.
May:
- The Kentucky Derby is won by Barbaro, who later suffers a catastrophic injury and is euthanized.
June:
- The World Cup soccer tournament begins in Germany.
July:
- The United States House of Representatives votes to censure Representative Tom DeLay.
August:
- Hurricane Katrina makes landfall in the Gulf Coast of the United States, causing devastating damage and flooding in Louisiana, Mississippi, and Alabama.
September:
- The New Orleans Saints football team returns home to the Louisiana Superdome for the first time since Hurricane Katrina.
October:
- The United States Congress passes the Protect America Act, expanding the government's surveillance powers.
November:
- The Democratic Party wins control of both the United States House of Representatives and the Senate.
December:
- President George W. Bush signs into law the Secure Fence Act, authorizing the construction of a fence along the United States-Mexico border.