A correspondent to Eric Alterman's blog says of Al Smith's 1928 run:

In 1928 Hoover carried 200 Southern counties for the first time in Republican history. The 1928 election showed that with the right cultural issue (Prohibition, anti-Catholicism, something along those lines) the GOP could court the white South.

In short 1928 marked a shift toward the urban/rural partisan split we see today.

I will therefore add anti-drinking and anti-Catholicism (reprised in 1960) to the the incredibly lengthy list of shibboleths the right has used to cajole people into voting against their own interests (states' rights, anti-ERA, bussing, school prayer, flag burning, pledge of allegiance, gay marriage, killing the brain dead, etc., etc., etc.). I'd love for someone to pull them altogether and just list them. I think the sheer fatuousness of the list would do some damage...