The Metropolitan Borough of Calderdale is a metropolitan borough of West Yorkshire, England. The population at the 2011 Census was 203,826. It takes its name from the River Calder, and dale, a word for valley. The name Calderdale usually refers to the borough through which the upper river flows, while the actual landform is known as the Calder Valley. Several small valleys contain tributaries of the River Calder.
Calderdale covers part of the South Pennines, and the Calder Valley is the southernmost of the Yorkshire Dales, though it is not part of the Yorkshire Dales National Park. The borough was formed in 1974 by the merger of six former local government districts, spanning, from east to west, the towns of Brighouse, Elland, Halifax, Sowerby Bridge, Hebden Bridge and Todmorden. Mytholmroyd, together with Hebden Bridge, forms Hebden Royd.
Halifax is the main commercial, cultural and administrative centre of the borough, with numerous high street chain stores, markets, central library, borough council offices, public transport hub, central police station, museums and the further and higher education college, as well as other major local organisations.