On the subjectivity of time

Kevin Drum has some interesting speculations about how we think about decades -- i.e., that they're not really defined by the actual calendar years, but about eras that are somehow definitive of that decade (but may be considerably longer or shorter). To take some noncontroversial divisions that seem somehow right to me,

30s: 1929-1941 (Great Depression)

40s: 1941-1946 (WWII)

Of course, he's using almost exclusively political dividers (with the exception perhaps of the Civil Rights movement), and the commenters suggest some other possible criteria. A fun thought exercise, even when more recent decades are harder to crystallize just yet...