Why is the presidential election always held on Tuesday?

When election day was selected by Congress in 1845 the country was mainly an agricultural society. November was chosen because the fall harvest was over and it was still mild enough for farmers and rural workers to be able to travel to the polls over unimproved roads.

Tuesday was chosen because most of the country had to travel a great distance to the polls in their counties. Monday was not reasonable because that would mean that people would have to start travel on Sunday and that would interfere with church services. The second Tuesday was chosen for two reasons, one, to keep election day from falling on all saints day and secondly, merchants were accustomed to doing their books on the first of the month.