National Washington Day is observed in the United States on May 10 as part of the National State Days project initiated by National Day Calendar. This day celebrates Washington's history and heritage as the 42nd state to join the Union, although it does not coincide with the anniversary of the state's admission. Washington, named after the first American president, George Washington, is located in the Pacific Northwest and is often referred to as Washington State to distinguish it from Washington, D.C. The state is unofficially known as the Evergreen State, a nickname suggested in 1890 due to its abundant evergreen trees, though it has not been officially adopted. The day acknowledges Washington's rich cultural background, including its history of indigenous tribes and European exploration. National Washington Day is part of a series of celebrations that begin with National Delaware Day on July 13 and occur weekly throughout the year.