PoliPundit has been following up on an interest James Taranto theory. I’m not sold on it yet, but it does make some sense.
The basic gist of it is that liberals have more abortions than conservatives, therefore the liberal population grows more slowly allowing an increase in conservative voters over time.
PoliPundit has shown that the Democrat advantage grew through the 1970’s and then started declining. So, using the same states as in 2000, Gore would have won 278-260 in 1970, 271-267 in 1980, and in 2000 Gore lost 267-271. In 2002, Gore would have lost 260-278.