1900-1909 : the age of big business -- 1910-1919 : the woman's decade -- 1920-1929 : the masses and tribalism -- 1930-1939 : the great depression -- 1940-1949 : birth of the atomic age -- 1950-1959 : the Cold War and McCarthyism -- 1960-1969 : challenging the establishment -- 1970-1979 : watching the world on TV -- 1980-1989 : "all right we are two nations" -- 1990-1999 : After the Cold War, the global society.