Why is it that it gets darker in Eretz Yisroel quicker than in the USA, making for a shorter Ben Hash'moshos?
Generally (without considering many other factors which may be involved) the closer the latitude is to the poles [i.e. the absolute value of the latitude is greater], the longer the sunset.
Therefore: Latitude at NY, NY = 40.7 Latitude at Jerusalem, IL = 31.78 NY, NY is closer to the poles, hence longer sunset.
Hope I understood the question and got the right answer...