This trend was identified in the mid-1990s when I published my early timelines (1994 for the first edition; 1998 for the second edition). The 1998 timeline (download a copy here) identifies a periodic shift from progressive eras in which human rights are advanced to regressive eras in which few advances in human rights occur.
The eras in which major advances in human rights occurred in the United States are:
- ~1785 to ~1815: The first major effort anti-slavery effort resulted in abolition in the northern states and outlawing of the slave trade.
- ~1845 to ~1870: Slavery in the southern states ended with the Civil War, while the women's rights movement began to develop.
- ~1895 to ~1920: The women's rights movement gained strength and in 1920 women were allowed to vote.
- ~1945 to ~1980: The civil rights movement brought about substantial changes in racial and ethnic equality, while the women's liberation movement made substantial gains in women's rights.