Dunnville was the site of a Cayuga settlement called "Detgahnegaha'gó:wah". The European settlement was originally built as the entrance to the Welland "feeder" canal and the town once boasted several water-powered mills and a once-bustling canal port. The feeder canal closed in the late 1880s and the last mill was destroyed and replaced with a condominium complex about ten years ago. There is an impassable dam at Dunnville which regulates the level of the Grand River at Port Maitland which, in the 19th century, also helped regulate the level of the Welland Canal (from 1829 until 1887 when the third canal began to intake its water directly from Lake Erie). Dunnville was incorporated as a village in 1860 and then as a town in 1900. In 1974, the town amalgamated with the townships of Dunn, Canborough, Moulton and Sherbrooke when the Regional Municipality of Haldimand-Norfolk was formed. In 2001, Dunnville and all other municipalities within the region were dissolved and the region was divided into two single tier municipalities with city-status but called counties. What was the incorporated town of Dunnville now consists of Wards 5 and 6 in Haldimand County.