Prior to Hoover's 1928 landslide victory, Catholics generally showed low turnout, and had no definite political affiliation. Smith did better with Catholics than Obama did with African Americans, and Democrats have counted on winning the Catholic vote, roughly 1/4 of the electorate (and growing) ever since.
Coincidentally, we can also thank Smith for the New Deal. FDR, who hated Catholics, rose to prominence winning the NY gubernatorial seat Smith abdicated and used his new coalition to push through his radical agenda.
Texas would dance like a miser (see what I did there) in front of a pay toilet because the choice boiled down to a Republican or a Catholic (and a wet one at that). They would finally decide to go with the Republicans because they didn't have no Popes.
The Catholic vote would be strongly segmented by geography. In the East they fed the big city machines but in the West they tended Republican.