The Boston Marathon is held in the city of Boston, Massachusetts on Patriot's Day, the third Monday of April. First held in 1897, it is the world's oldest annual marathon.

Administrative Professionals Day® highlights the important role of administrative professionals in all sectors of the modern economy worldwide. It is on the Wednesday of Administrative Professionals Week®, which is on the last full week of April.

Oklahoma Day, which is annually held on April 22, commemorates the date when the "Oklahoma Lands" area, which is now the state of Oklahoma, opened for European settlement.

https://www.daughtersandsonstowork.org/ Take our Daughters and Sons to Work Day is not a public holiday. Businesses have normal opening hours. Each year on the fourth Thursday in April, National Take Our Daughters and Sons to Work Day encourages parents to take their children to work. This annual event is an educational program in the United States…

The United States was one of the first countries in the world to celebrate Arbor Day, a holiday dedicated to tree planting. National Arbor Day in the USA is celebrated on the last Friday in April. Besides, each state celebrates its own state tree planting holiday. Arbor Day was founded by Julius Sterling Morton, a…

OIC will be closed in observance of Memorial Day.