Summit, New Jersey is seated in the Watchung Mountains, a series of hills topping out at about 500 feet, according to Wikipedia.
Google calculated I was about 380 feet above sea level when I took that photo of lower Manhattan.
Google also estimated I was “approximately 23 miles” in a straight line from lower Manhattan.
So let’s do the math using Wikipedia’s page of calculations determining horizon.
If d is the distance to the horizon and h = 380 feet, the square root of 380= 19.49, times 1.22 = 23.78. Accurate within ¾’s of a mile.
Not bad, Google.