On this day (November 4) the following presidents were elected:
Note that there are 28 years between each of these except Cleveland and Coolidge. That makes sense because 28 years is seven election cycles, so every seven years the fourth of November would fall on a Tuesday. But why 40 years (10 election cycles) between Cleveland and Coolidge?
The answer to that is because of leap years. Leap years come around every four years when a year is divisible by four. So leap years come as often as elections. But when a year is divisible by 100, it is not a leap year unless it’s also divisible by four. Thus, 1700, 1800 and 1900 were not leap years but 2000 was. However, there was an election in 1900 but because it didn’t coincide with a leap year, it threw things off and it took until 1924 for November 4 to fall on a Tuesday again.