What makes a decade?

Kevin Drum takes a gander at America's 20th Century:

• 20s: 1919-1929 (League of Nations vote to stock market crash)
  
• 30s: 1929-1941 (Great Depression)
  
• 40s: 1941-1946 (WWII)
  
• 50s: 1946-1963 (Churchill "Iron Curtain" speech to JFK assassination)
  
• 60s: 1964-1973 (Civil Rights Act to end of Vietnam War)
  
• 70s: 1973-1980 (1st oil shock/Watergate to 2nd oil shock/Iran hostage crisis)
  
• 80s: 1981-1989 (Reagan election to fall of Berlin Wall)
  
• 90s: 1990-2001 (Berlin Wall to 9/11)
  
• 00s: 2001-

This is a great list, and the only change I might make is splitting the "50s" in two sub-decades (as 17 years is a bit long for a decade):

• 1946-1954: Partisan balance (control of Congress changed in 1946, 1948, 1952 and 1954)
  
• 1955-1963: The emergence of a permanent Democratic majority

Otherwise, I agree with his list.