National Delaware Day is observed worldwide every July 13 to recognize Delaware as the first state to ratify the Constitution of the United States. Established by National Day Calendar in 2017, this holiday celebrates Delaware's historical significance, particularly its role in the founding of the nation. Delaware, named after Delaware Bay, was originally inhabited by Indigenous tribes such as the Lenape, Nanticoke, and Susquehanna before European colonization began in the 17th century. The state became the first to ratify the Constitution on December 7, 1787, earning it the nickname "the First State." National Delaware Day is part of the National State Days project, which aims to honor the history, culture, and heritage of each state in the order they joined the Union. Celebrations typically occur in the week following Independence Day, highlighting Delaware's unique contributions to American history.