When your lawmakers spend their days doing the bidding of developers and large corporations, and only sometimes get arrested for it, it can be easy to forget that we live in a democracy. Even easier to forget: though the presidential primary is not until April 19th of next year, the deadline for changing one's party is this Friday.
An obscure bit of election law (Section 5-304) requires voters to change their party enrollment prior to the registration deadline for the general election in November the year before the primary, giving New York the earliest change-of-party deadline of the 11 U.S. states with a closed primary system. New York is also the only state among those 11 where the deadline doesn't fall within the same calendar year as the primary.
NY State Board of Elections spokesman Tom Connolly couldn't pinpoint when the rule went into effect, but said he believed it was created to discourage "party raiding," where activists from one party change affiliation en masse to screw with an opposing party's primary results.
"My understanding is the reason why [25 days before the general election] is the date that it is is to prohibit party raiding," he said. "Even if somebody were to change their enrollment this year so that they could vote in a specific party's primary next year, they're stuck with that party enrollment for the likely federal primary that's going to happen in June, then also the state primary that's going to happen in September."
Again: if you aren't affiliated with a party, or want to change parties for the upcoming presidential primary, you have to do it before Friday. It is likely too late to register online through the DMV (its website says to "allow six weeks" to hear back from the Board of Elections), so late-changing voters need to register by mail or in person at a Board of Elections office near them. The relevant form is this PDF. Update: The NYC Campaign Finance Board tells us, "Registrations filed through the DMV voter registration portal will take effect like any other if filed before the deadline. The sentence on the DMV website refers to how long it takes the BOE to send notice/confirmation of your registration - it is the same six weeks whether you file online or with a paper form."
Bernie Sanders supporters have made a whole website dedicated to letting slacktivists, coffee-shop socialists, and Green Party members know that for their vote to count in New York, they have to become Democrats. The same applies if you're a 4chan user who voted Libertarian in 2012 but want Donald Trump to get the Republican nomination so he can continue to troll the world.
People who need to register for the first time have until March 25th, 2016 to be able to vote in the April primary. This November 3rd, the few voters who turn out will get their pick of judges. A few state legislature seats and the Staten Island District Attorney's Office are also up for grabs [pdf].