Tomorrow is election day. Mid-term elections don’t usually generate the same attention as presidential elections, but many schools will still be closed in observance of the event. But why? Election day is not a federal holiday and schools are certainly not obligated to close.

There are a variety of reasons for schools to be closed on election day. The most common of which is the fact that schools often serve as polling locations themselves. Centrally located, government-owned buildings with large indoor spaces and parking are often the obvious pick when looking for a place for thousands of people to go and cast a vote. Not to mention the fact that most people in the neighborhood generally already know where the local school is. A school doesn’t have to close just because it is a polling place and many of them do stay open. However, it is easier logistically if the students aren’t there as many schools report that the extra activity on election day makes operations difficult.

Another reason schools close on election day is to give teachers and other staff the opportunity to vote. Many polling places have hours that make it difficult for people to cast their ballots. There has been a national push to make election day a holiday for that very reason.

Finally, with all of the controversy around the last election, there have been credible threats to polling places. Threats of violence and fears around voter intimidation have some polling locations taking precautions. Schools are no exception.