One of the arguments for a Trump nomination is that he could win New York State. New York is quite a prize. It still is in the top 5 in Electoral votes.No Republican has won the state in a presidential election since Ronald Reagan’s near clean sweep in 1984. George H. W. Bush came close in 1988 with a loss by 4%. It got considerably worse after that.
New York holds a closed primary and the time to change party registration was in 2015, well after the first state contests. Many independent or Democrat Trump supporters were out of luck. Also, the Democratic Party primary was slightly more competitive. However, there is a pretty stark indication of how hard it would be for Donald Trump to win New York in a general election.
Democrats outvoted Republicans 1.7 million to 850,000, about a 2:1 ratio. Not only did Hillary Clinton get more votes than Trump, Bernie Sanders got more votes than Trump and John Kasich combined. Trump may beat polls and expectations, but taking NY in November would have to be a tidal wave of proportions that have never been seen in the Trump phenomenon.