Marlborough Anniversary Day is observed in the former historic province of Marlborough, New Zealand, on the Monday closest to November 1. This day commemorates the anniversary of the province's separation from Nelson Province in 1859. The region, located in the northeast of the South Island, was first explored by Captain James Cook in the 1770s, who established contact with local Māori iwi. Permanent European settlement began in the 1840s, particularly in the fertile Wairau Valley, leading to significant historical events such as the Wairau Affray in 1843, a violent conflict between British settlers and the Ngāti Toa tribe. Although the provincial system in New Zealand was short-lived, the anniversary is celebrated to honor the legacy of the Marlborough Province and its early settlers.