“Data show a decline in the nationwide share of registered Democrats since the party’s peak in 2008, which coincides with an increase in the share of registered Republicans. As of July, there are 120.8 million registered voters in the 31 states that track party affiliation — 47.1 million (39%) of them are Democrats, 35.7 million (30%) are Republicans, and 33.9 million (28%) are independents. The rest are registered as supporters of a third party.”