Voting opens for the 2016 U.S. presidential election in a matter of hours, as months of campaigning, news coverage, and revelations draw to a close. On a special segment of Last Week Tonight, John Oliver’s show asked on Saturday why exactly the country votes on a Tuesday.

It all comes back to 1845, when a law was passed proclaiming that presidential elections would always take place on the Tuesday eight days after the first Monday of the month in November.

“People had very limited access to move about polling stations, or where they would vote would be extreme distances,” said Scott Lansell, international election expert, on footage aired from the Early Show. “They had to find a way of making election day a day they could accomodate into their schedules.”

The weekend was out of the question due to the Sabbath, so Tuesday was chosen so voters could have Monday free to travel to their nearest polling station. The practice continues today, over 150 years later.

The date has caused serious issues for voters in the past, who have struggled to find the time off work. At the Oakland university precinct in 2012, voters waited for north of three hours, and these lines can impact hourly workers who need to take time out of their schedule just to make it to the booth on time.

There are signs that this is changing. Thirty-four states and the District of Columbia now allow for early voting without needing an excuse, so voters can cast their ballots on a day more convenient to them. Other states may allow for absentee voting with a valid excuse: In the state of New York, for example, voters are qualified to vote via absentee ballot in the case of permanent illness or disability.

Last Week Tonight airs Sundays on HBO.

Photos via Last Week Tonight/YouTube

Mike Brown is a London-based writer with a passion for tech, politics, and photography. After studying Journalism at Columbia University in New York, he returned to the UK to cover the news as it happens around Europe. His work has been featured in IBTimes, Neowin, Building Magazine, and more.