In the United States, public holidays are set by federal, state, and local governments and are often observed by closing government offices or giving government employees paid time off. The federal government does not require any private business to close or offer paid time off, as is the case for most state local governments, so employers determine which holidays to observe.

Opening Day is the day on which professional baseball leagues begin their regular season. For Major League Baseball (MLB) and most of the American minor leagues, this day typically falls during the first week of April, although in recent years it has occasionally fallen in the last week of March. In Nippon Professional Baseball, this day typically falls during the last week of March.