river rising at Malham Tarn (lake), in North Yorkshire administrative county, historic county of Yorkshire, England. It drains the central Pennines and flows southeastward through West Yorkshire metropolitan county and across the southern part of North Yorkshire to meet the River Ouse at the border of the East Riding of Yorkshire. The upper reaches of the river are in a deep, troughlike valley known as Airedale; the dale's scenic beauty makes it a tourist attraction, and its agriculture is concentrated on dairy and poultry production. After leaving the Pennines, the river crosses the Yorkshire coalfield and is joined by the River Calder, its major tributary. Leeds is the principal city on the river.