Just three decades ago, when politics weren’t yet so polarized, all 50 states were up for grabs, swinging between parties from one election to the next.
Since 2000, 40 states have voted for the same party’s candidate in all four presidential elections. By contrast, in the four elections between 1984 and 1996, states “swung” more often: only 17 states voted for the same party’s candidate in the four consecutive elections during that period.
Increasing political polarization is a big factor in the swing state phenomenon. The roots of current polarization stretch back to about the 1970s; since then, the parties have become not only more ideologically sorted but also more ideologically divergent, and their members more hostile toward the opposing party.