The first day of autumn does not have exactly 12 hours day and 12 hours of night. There is about 12 hours and 7 minutes of daylight, depending on what part of New York State you are to celebrate the autumn equinox due to refraction of light on the earth's atmosphere. This is The Town of Massena will have the longest day in all of New York State, at 12 hours, 7 minutes and 54 seconds. The Borough of Staten Island will have shortest day, at 12 hours, 7 minutes and 29 seconds. On Wednesday, September 27th this reverses -- the day will actually be slightly longer in Staten Island then Massena.

This article explains why "Equinox Does Not Have Exactly 12 Hours of Daylight and Night". https://www.timeanddate.com/astronomy/equinox-not-equal.html