The twentynine states with registration by party, plus the District of Columbia, reported in October or November 2010 that 73.5% of all voters are registered Democrats or registered Republicans. This is the lowest percentage for the two major parties since before 1980, and probably the lowest ever. There was no such thing as registration into political parties, on voter registration forms, before the 1910’s decade. The idea that people should be asked to choose a party on a voter registration form did not arise until after the start of direct primary elections.
At the spring 2010 tallies, the two major parties had 73.8% of the registration. In October 1992, the two major parties had 80.7% of the registration. The December 1 2010 printed Ballot Access News will contain registration data by party and by state.