The change comes after the state's presidential primary in February, where unaffiliated voters joined a party if they voted for a candidate.
At that time, nearly 60 percent were unaffiliated. Now, the figure is about 45 percent.
The overall registration for Tuesday's state Primary elections is nearly 5 million, up more than 2 percent since February.
Democratic registration rose by more than a half-million people to nearly 1.7 million, accounting for one-third of all voters.
Republican registration rose 18 percent and now exceeds one million voters. The GOP is still outnumbered by Democrats by a 5-to-3 margin.
