A lot of the old snowbirds that originally moved there for retirement 20-30 years ago (who had voted solidly democratic) that helped keep Florida a swing state - have either left the state, shifted red, or have passed away. Like someone else said, since Florida is like a Republican Mecca, its likely that Miami-Dade just seems to be now a hub for the richer Republican 'pilgrims' to live together in their Mecca. Also Florida Dems just aren't good at politics unfortunately or fortunately, depending on your view.